First of all, it is not easy to predict bitcoin price. Even many experienced persons fail to predict it correctly. If you want to earn with trading you need to first learn all about trading. If you are not comfortable in trading then you can just hold the coins and wait for them to rise. Everyone can earn with bitcoins, its just which path you choose to earn them.
Not only by the investors Pump and Dump but sometimes it is based on Bitcoin value. As long as the price of Bitcoin is kept increasing we will be making some good amount of returns but once the price of Bitcoin is losing it will effect on all other altcoins. It is always impossible to guess the exact prices of altcoin when they are decreasing and when they are increasing.