3 years is an eternity in Internet years. If there's a failure to generate a MVP like you mentioned in 3 yrs (one should've been able to get something out in 6 months to a year at most to test the markets), then it's time to cut your losses. Tenacity and willingness to not give up is one thing, but it's also another to know when to call it quits.

Each day spent without releasing an MVP is a day of lost opportunity that could've been spent elsewhere.

A large company isn't necessarily a bad thing either as it'll help you accumulate savings in your early years (which are the most important years to accumulate savings so you can put it to work generating interest, capital gains, etc. so that the power of compounding works passively for you). There's some chart out there somewhere comparing savings compounded early on vs. someone that started later and the difference when you retire is huge.

Plus sometimes you learn alot about how big companies processes work, how they make purchases, contacts, etc. that will help you later on in life if you do intend to go back to a startup world or start your own.

Good luck!