I also buy/sell altcoins with my btc and earn a good profit. I bought ETH when the price was 0.03 and now the price reached 0.06. It's much better than lending money.
Trading can be much more profitable than lending..
But the main fact is right time entry to the market.
As you have entered the ETH market in the right time, so you have big profit.
If op want to do lending then I can suggest to divide the capital in two parts, 1 part for polo and the other part for lending section in this forum.
Create a thread and offer your loan service.. But just keep your eyes open for scammers. If needed then borrow a eye for yourself also..