I salute you!
I just turned 50, but I never feel I can pull the trigger. The only thing really keeping me from doing it is the cost of health insurance. I've got 15 years before I can get on Medicare, and 15 years of privately purchased health insurance for the family is just not do-able.
Thank you! Health Insurance is certainly the big one. It took me a while to save for that. There are some ways explained by the FIRE community to reduce the amount you pay through the subsidies, but these could vanish at any time so you have to be prepared for that.
The tight coupling between employment and health insurance is a huge issue for the US, and has been for as long as I can remember. It's a pretty big ask of someone to "become an entrepreneur; either pay your own premiums or go without!"