If you have asked this question 6-7 years back, you may be had made fortunes by now
but now no easy way is there, either invest, trade or do freelancing for bitcoins.
Well if people would have know before then everybody on earth would be billionaire by now. Do you even know if you buy now in next 5 years you may again become billionaire which is possible if btc price just keep on rising. So you should keep buying every month either btc or some good altcoin which you think is available nowdays cheap and have a good future. Also you can join some signature campaign and do freelancing work as per your skills and get paid in btc.