I just invested approximately $50 in freebitco.in to gain interest payments. Let's see how it is going to end up in a couple of years after btc goes nuts
You definitely won't get much than you get now
And if Bitcoin flies to the moon, the interest rates are likely to decline. I don't know your reasons for making this investment (I mean the interest accumulated will be small to make a real difference anyway), but have you tried investing in the casino bankroll of the dice sites which allow such investments and pay dividends from their earnings? While it may look riskier, but when you come to think of it, it is still the same systemic risk mostly (of hacks, inside jobs, extremely lucky whales, etc)
The reason I chose freebitco.in is because it has been around since 2013. More than 5 years now. You won't find many businesses built around bitcoin which lasted more than 2 years.
I haven't tried any casinos as an investment yet. The one I would trust is primedice/stake but as far as I know they don't accept investors and I don't know any other trusted casino. There are a few but not as trusted as primedice imo and like you said the returns are still at risk.
What freebitco.in offers is risk free (other than the risk of freebitco.in turning itself into a scam which applies to almost every investment) and the motivation here is to collect as many satoshis I can while it is still cheap. I am not calculating the wealth in terms of dollars here. I simply want to get all the satoshis I can because I know they are going to worth a lot in a few years.
I remember freebitco.in used to give hundreds of satoshis. I made a mistake by not collecting those and now I am not making the same mistake again.
I might increase my investment to $100 but probably won't go higher because of the risk.