Earning too little is a problem for travel hacking. First, travel hacking is principally based on spending. If you do not spend enough, you will not earn the sign-up bonuses travel hackers use to rack up points. Most of the top credit cards have minimum spends around $4000 or $5000 within the first 90 days in order to earn the sign-up bonus. The minimum spend target is higher for business credit cards. If you are earning $24,000 a year, the minimum spend is a tall order without resorting to manufactured spend. It would be a struggle even at $36K.
Another thing to consider is that you may not qualify for the desired credit card based on your income. Never mind playing the game. First, you have to be in the game. With insufficient income, your chances of getting the top tier credit cards are diminished. Thus, you would not be able to earn points for your purchases.
The final consideration, if you have low income and are trying to get into travel hacking, is that once you get the sign-up bonus, it takes forever to accumulate additional points. Again, the game is based on how much you spend on your credit cards. Without the sign-up bonus, you may be earning one point per dollar.
Most cards will yield about one cent of value for each dollar spent. Do the math. 20,000 points are the equivalent of $200. In other words, once the bonus offer is over, you may have to spend up to $20,000 to stay at a decent hotel overnight. Assuming you get double points, you are still spending $10K. And, if you splurge $550 per year on the AMEX Platinum, you would need to spend $4,000 at 5X points to get 20,000 points. See how that does not add up? Spend $4,550 to get back $200. Successful travel hackers are able to rack up sign-up bonuses and additional points simply because their spending is at the level that a $400+ annual fee or two is reasonable. Or, they can meet the minimum spend on multiple cards without hardship.
My aim here is not to burst your bubble. Travel hacking can get you better value from your points and miles than redeeming them with your credit card. To do this you transfer the points out to an airline or a hotel. However, it still requires you to accumulate a lot of points to make it all work.
I do not know how to calculate what your income should be for you to consider dipping your toes into travel hacking. It is a much different story if you are earning $36K and raising a family versus earning $36K and living with your parents. The numbers will depend largely on your situation. Obviously, the more you earn, the better. And this absolutely depends on you paying off the card every month. Paying interest will cost you more than what you would get in points and miles.
This is one of my frustrations when reading blogs by writers who have reached financial freedom and who have retired early to travel the world. The general sense they convey is that if they can do it, so can you. They are not wrong. However, they started from a much different place. There is a major difference in savings when you earn $24K versus $100K. With hard work and sacrifice, it would only take you a few years to save up half a million dollars or more when both you and your spouse are high earning software developers. In contrast, if you are a small town librarian, it could well take you 40 years to do the same. It is somewhat cruel to let readers believe that anybody can get into travel hacking at any income level. While technically true, there will be wildly different outcomes based on income.
At the other end of the spectrum, high-income earners do not have the time to spend hunting for bargains and going through financial contortions to get points. If they want to travel, they will pay for it. If they happen to accumulate enough points for a free stay or a free flight, it's just icing on the cake that they already ate and have too.
A couple of years ago, I would not have been the best candidate for travel hacking. Things have improved for my family and me. Thus, travel hacking becomes a viable option. With the right combination of credit cards and strategic spending, we can get better than one percent yields. But, it still takes us time to accumulate the necessary points. And, even if we have the points for free or discounted flight and lodging, there is still the matter of dining and entertainment on the trip. You can save a lot of money by redeeming points; but, once you arrive, you will want to do more than window shopping.
Something else you should keep in mind is that many travel bloggers have some kind of business that pays for their travel, either directly or indirectly through accumulated points and miles. They sell advertising, earn affiliate referral commissions, do some web development during their travels, host webinars, or any number of activities to generate income.
What you should take away from all this is that you should strive to increase your income as much as possible, which includes having a business. All this is to help you generate the necessary spending needed for you to accumulate meaningful amounts of points and miles while also being able to put money away in savings. Businesses are particularly good at spending money to make money.
Assuming your business is profitable, it will generally require you to spend money to make money. You could spend money on advertising, outsourcing, equipment, supplies, hosting, phone service, and many other things that you can charge to a credit card in order to earn more money. You generally want to be in business to make a profit. But, you do not necessarily have to be in business to become rich. If your business breaks even or generates a modest income, yet it affords you the ability to travel, your life would still be enriched.
In summary, not earning enough will hamper your ability to travel hack. If you cannot rely on getting a raise, your best bet is to start a side business that churns through cash via travel credit cards and is profitable. That churn can generate the spending you need to do what the travel hackers write about. Thus, you could overcome the income requirement for travel hacking.