If I'm not wrong, the average yearly ROI of something like S&P 500 has been around 7-8% over the last 70 years. Since you're French as well, I can tell you tha

If I'm not wrong, the average yearly ROI of something like S&P 500 has been around 7-8% over the last 70 years. Since you're French as well, I can tell you that here it gives about 4-5% in yearly returns. So it's not unheard of returns with traditional asset classes. As far as I'm aware, the money in that specific case comes from interests paid by those taking loans (from the funds that's you're putting out) or from staking rewards (in the case of staking cryptocurrencies using proof of stake).