To be honest, is probably easier and more successful to consequently reduce spending that to found a startup that will net you money in X years. Startup is hard work, 80+ hours a week including events networking etc.
You won’t have a life no holidays etc, and no certainty that is going to be paid off. So it may be easier to attack your spending, that would still leave you some free time and you could sleep better at night than with a startup.
I worked for a startup in 2011 for one year, and I saw the founders. They basically never slept or had a life. We worked out of the roof floor of one of the founders mom’s home.
After 8 years they are successful, their business is exploding and still it is all revenue, not profit. They need to reinvest everything, hire new people and are still making a normal salary.
I have no doubt in 5-10 year they could sell off the company for x millions and be set for life, but they rode a high risk venture with no social life for almost 20 years.
If you cut down your spending to 25 % of your income, you may be FIRE in like 10 years.