you never make money on Shabbos. you THINK your making money but hes not.
his riches might be him getting his reward in this world instead of in the true future world of olam haba. due to now him being such a mechalel Shabbos for such a long time R”L
Tell him if he wants to do teshuva for his great sin (which is chayav death just for doing it one time on purpose) that he needs to give all his money to tzedaka & remove any benefit he still has from all those shabbosim of chillul Shabbos & then he still needs to do teshuva from the heart with fasting also.
HATZLACHA
(its never too late to do teshuva, kings achav & menashe did teshuva after 30 years of sinning & causing klal yisroel to sin. & their teshuva was accepted why? because it was sincere teshuva)