Have you ever had the perception passive investments in general (stocks, real estate funds...) generate a very low profit margin?
It stays around 0,6% monthly profit, what means you need 100,000$ invested in order to generate 600$ bucks a month.
If on average I'm going to get $600 per month out of the $100,000 I have to invest, then that's not low, but it's high for me and I would certainly be willing to do it especially since this type of investment is clear and doesn't lead to fraud.
This means that with an investment capital that is less than the amount you mentioned, I can still get a very decent return for me if I add it up every month until it reaches 1 year. Usually 4 years of investment, I can estimate how much I will get.