Made a series of bad financial decisions. Feels very behind

Just some background:

34 YO military dentist(married with one spouse and a young child). This summer will be my 6th year being active and I originally wanted to separate after serving my obligation(for dental school scholarships) and buy a house so I never contributed anything to my TSP until 2 years ago(5% to get the match).

Also, obviously I opted out of the high 3 and that’s a mistake as well since I’m planning on staying till 20(likely retire as an O-5(maybe O-6) now.

TSP is around 25k, 250k cash, and 120k brokerage(currently down 15% due to series of bad stock picking). I also impulse bought a luxury car in cash for 40k and don’t even drive it anymore(I gave it to my parent) because of current duty station.

I just feel like I would be at around 600k now at least if I just invested in the tsp or brokerage(s and p). I really want to start over fresh. Also currently zero debt because of the scholarships.

Should I just use the cash(currently in HYSA) and lum sum it on the VOO or VTI?

Any advice is appreciated.