If you want to start a business and make money, do not rule out old economy, and bootstrapping. Whatever VCs say.
https://www.forbes.com/sites/nathanvardi/2018/11/19/how-a-my...
If you have profits sufficient to fund R&D you could also potentially approach your investors about buying them out with those profits. Something like "It has become apparent that this company is never going to provide the growth you are after. Instead, every quarter the company with pay you $X in exchange for N of your shares. After two years the company will have bought back the last of your shares and you will have twice your investment. We enjoy running the company and intend to do that for the foreseeable future despite the limited growth."
I know VCs are aiming for home runs and 10x+ returns but trying to get someone to shut down a business like that seems short-sighted.