You can grow your tbc when you invest for some site that realy are paying in return, but be careful theres a lot of investing site now that is a scam. Also you can buy and sell btc, this is the time to buy btc while the price is still low because sooner or later it will get so much more expensive. But take care also because there are lot of scammer now. You can also gumble with your btc it is an easy way. But ofcourse there is no assurance if you can win or not. You can trade something in exchange with btc. There is a lot of way to grow your btc. Don't just keep it will not grow without running it.
Are you talking about cloud mining or doubler sites to invest? And if that is the case then I will recommend you never to put your money on those sites as everyone of us have got scammed at least once from those sites in the past as we were hoping that those sites will help in multiplying our bitcoins quick and we are still waiting for that.
I agree, most of investment site swas turned into scam. Probably they will pay you for few first month but they can turned into scam anytime. There is no supervision for them. So better we do trading to grow our btc.
Either do your own or if you invest in some site than at least read how they claim to generate profit for you ?
I mean if a site just says that they have a special method then probably a ponzi while if a site explains how they are going to generate profits then people can debate that and discuss the topic, while growing bitcoins we need to remember that the risk should be minimal for profit, even though if the profit seems less.