A good way to minimize the risks is not invest real money (or invest a little amount).
With some efforts you can earn bitcoin from faucets, forum signature campaigns, glambling (not recomended), trades, etc...
After achieve a good bitcoins amount you could invest It. If you lose all, you don't lose your money.
If a person will not invest real money then he will not take any benefit as if someone will start with nothing then he will not earn faster and he will then feel too late and slow and will regret which I am feeling. But if someone will want a faster profit then he have to invest some real money.
Money isn't always the investment that you need. For example, when you get a job, you don't necessarily have to pay them money. All you have to be is qualified. When you're qualified, you just have to work and then you're going to earn money. Your pay rate is depending on your position on your work. The investment in most jobs are knowledge and time, but not always money.
But if we're talking about getting shares in a company or any of that kind of investment, then you're right. The more money that you invested, the faster you'll get profit.