Of course invest day by day bitcoin are getting bigger and bigger if you wait your money will be stagnant as well as your profit. But if you invest wisely you can make money and profit as well.
If you convert your fiat into bitcoins and safe them, it is also an investment and it is the safest investment. If you plan to invest in a site which can give you profits monthly or weekly, then be careful as you can really be scammed as most investment sites of this type scam.
I would advise to all that keep your bitcoin safe with yourself as bitcoins are now precious item.