We know the reason...he wants to live a peaceful life with all the money he’s got. They say when you have a lot of money, your life is at risk, either from getting robbed or worse, getting killed. Satoshi doesn’t have to deal with that kind of fear despite owning a huge amount of Bitcoin because he chose to stay anonymous. He’s probably enjoying life to the fullest without even needing to work, living the best life possible, especially if he’s in good health.
What's actually Satoshi get benefit from his own invention? yes he own like 1 Million of Bitcoin, but AFAIK he never sold his coins, so how do he live peaceful life with the money he got? Satoshi actually didn't receive any benefit except he start to sell his coins.
It's actually sad that he invented something that didn't give benefit for him.