Although it doesn't happen that much, there will eventually a coin that doesn't cost that much right now and will skyrocket in the future. An example of this is bitcoin but the time to invest for bitcoin has passed. To become rich using bitcoins, I can only see it possible by investing in an altcoin. You can also build your own company and offer services online but that will require a lot of time, effort, and money.
Yes indeed.. there are a lot of ways / options for you to invest in bitcoins but still you need to put a lot of effort to become rich. Ofcourse when you invest there are ups and downs like in trading you need to predict the value of bitcoin and its very risky too.
There's many method actually but choose the safest one and take it slowly but sure.