Focus on B2B products, if you are able to convince 5 customers to pay 5k per month or 50 customers to pay 500/month it's enough for you as a solo entrepreneur.
B2C is another beast and indeed needs tons of capital.
Isn't B2B even harder when you have to convince businesses to use your product instead of existing one, so they have to completely move to your product. Then of course attend the meetings with them and so on. I'm not a salesman and for me it would be mission impossible. I don't feel comfortable in that role and I'm bad at it
You can make one feature that is lacking and that customers want. Usually the big competitors have apis and plugins so you just integrate it to the larger product
Businesses, especially big businesses, are just people with a problem. The nice thing is they’re not spending their personal money so they’re more flexible. If you want to take over their billing system, that is a huge project and will take lots of meetings and time and you’ll fight huge companies. So focus on a small problem those people have - keeping track of one single resource, updating printer drivers, a desktop pop-up notification when the printer is low on ink, etc, etc. A $1 million market is too small for big businesses to chase but can make you quite comfortable.