Start by looking at the market and statistics of what software people or companies are making money on.
Then, look at how they market and sell it, and what offer they present to their customers. Reverse engineer the customer journey.
Now you still don’t start programming(!). You wanna first create your own offer through one of the viable marketing channels you created. But instead you’ll ask people “If I had x-software, would you buy it?” Or if youdon’t do in-person or telesales you run test-ads online or in newspapers to see whether you get the expected clickthrough rate of people being interested.
Once you figured out that way what people want, you start building a small low-effort prototype and give it to the most-desperate, early-adopter cusomers.
From there you improve the software bit by bit making it more and more delightful for the cusomers to experience. You may have to pivot into a new customer segment or a different application after you gained some knowledge and experience about the market
If you put in work you will get paid for your time.
You can do it with less than 500, making a social media account and uploading engaging content, be it blogs or YouTube (filmed on your phone and edited with free software) you can start a carreer. You can do all the reaearch for it online too.
Of course it rakes a lot of time and commitment, like, your lifes-work-type of commitment and on that time span $500 is very insignificant. Considering all the other sacrifices and opportunities you let slide