You will encounter two very common problems among others, at least these two I know:

1. A newly created token which has not been listed may be locked in the wallet. The owner will not be able to send to anybody and this is coded into the smart contract for a specific date when the token unlocks. This is to prevent the specific grey market that you are actually interested in.

2. There is no guarantee that buying those tokens early before trading starts on exchanges means that you get a upper hand. Yes you might benefit from the first flip but are you going to bet on being able to catch the first wave, because you are not going to be alone there.

Also the risk involved in getting into projects that are vaporware are very high. You might end up being some shitcoin and end up with your money stuck in a worthless asset. There are other places to invest and this is defenitely not a wise choice.