Splat being in his 40's and self sponsoring a type training is in no way a bad thing. If you mean spending 20k and having approx 20 years left in your career that equates to 1k per year and most defo salaries are in the region of 38k - 48k on a jet. Depending on the type of outfit splat works for he may well have his command in a few years ..... that's generally 70 - 80k with expenses.
Not a bad investment 'if' it all pays off!