Dadice takes a 10% fee on the investment when you divest.

Are there weekly auto-commissions like JD? Or just when divesting?

Only when you divest. You get the full amount. You can also divest at any time, even if it is minutes after the investment is made.

This means that there is only 10% taken from any profit you made on your investment. If your investment went lower, there is no 10% fee charged.

If a user makes 1000 btc investment and never de-invest for 5 years, how will you earn? You have to implement it but you know.

I don't think that would happen. Besides the entire investors bankroll is just part the total bankroll.