If I had enough money, would buy an apartment, and do airbnb renting in it. Know some people doing it, and brings nice money with not too much work.
This is a good alternative investment mate aside from crypto. Investing in real estate is a sure profit although it needs a big investment amount. The best investment that we should start should fit on our capabilities and personality. If we don't have enough funds, we can start a small business like buy and sell.
Many sources are around us but we should think productively and should choose the most valuable currency if we are able to invest there which will make huge profit. On the other hand if we are satisfied with money then we should spread our portfolio which is most productive thinking. Besides the Bitcoin there are many other coins, Ethereum for long term and Altcoin, Litecoin etc are best for short term.