You could always consider investing or even starting your own gambling site. Whilst it is likely a big risk the returns can be huge (especially if you create your own site).
I can imagine. Trading must be done conservatively and after all the research and risk management is taken into consideration - something that took me some time to master as well. Your best bet is to reach out and find sources of passive income (providing bitfinex btc swap for example, but that will at best net you 0.05% profit a day, and with 50btc, will net you 0.75 btc or barely 1.5% a month - very low). Lending is a good option if you know who you are talking to (ID, etc).
I am personally doing trading and investing on btc movements, and so far I have been doing quite well. I previously had an account here used for that purpose, with loan history to prove that I can do business with decent % return every month (8-10 %). I was unsure of security after the last bitcointalk.com hack so I created a brand new account. The largest loan I concluded was about 8 btc in size that lasted over a few months, so if you are interested in making passive income with interest on loans, I will be happy to accommodate the terms. If you wish, I can also do phone calls and ID verification (would be an easy thing if you lived in US especially), or if you live close, even in person interview.
Let me know if you are interested via pm

Can you tell me more about your trading strategy via PM? I've got about 20btc I want to invest in trading but haven't been that sucessful so far (minimal profits). I was planning to just hold my btc as an investment but the market seems to be pretty stagnant and doesn't seem to be going any where soon so I'd like to make my money work for me now by trading.