How many years of 12-hour days will it take to realize your $250K?
If you were working 9-5 and I offered you a night job for 4 hours a day, would you take it? If I promised you $200K if you did the night job for two years, would you take it? If you got $0 if you quit before the two years was up, would you take it? I can pull out of the deal at any time in the next two years.
I know a guy who scrubs toilets from 4am-8am M-F for $10/hr. He expects that to turn into $100K in about 5 years with careful investment. If he just stuck it in a 0% savings account, it will be $50K in 5 years. Financially, this seems to be a smarter plan than yours. But if you really enjoy what you do in your four extra hours per day, and you really hate scrubbing toilets... maybe your way is better. The point is, there is lots of room to question your choice.