Also you can join signature camping, do free lancing work and get paid in btc. If you have skill then can do trading and with the right side of buy/sell you can make money easily. Once you have few btc then you can sell it or hold it as the price rise so is your value of btc also increases.
Very true in trading you can make good profits in quick time but before that you need to go through a good research and choose your coin wisely and if you successfully manage to do that then you will be making huge profits and apart from trading I don't see any other better thing to make regular profits.