He probably means that if you trade instead of mine you will make more money. Which is true, however most likely you will end up losing all your money trading like most people around here who try to day-trade.
Either way, back to your mining question.
Right now you can maybe earn $5/day with your GPU but it won't always be like that. ETH can lose half its value and you will make $2.50/day. The transactions for ETH can become less congested and your reward can also fall to like $2.50/day even if ETH stays at $1800.
Overtime as more and more GPUs start mining ETH, they all get a fair share of their profits. So if twice as many people start to mine ETH in the next 90 days, then your profits will be $2.50/day even if the transaction fees stay the same and ETH stays at $1800. This is called difficulty and its to keep the supply constant. Try to understand this before you spend $40K.
That is an interesting point. I am mining Bitcoins and currently at approx. $25-28/day. Few quick questions:
1. When you say it can lose half its value, you mean the halving of Bitcoin (that is supposed to occur in 2024)?
2. And when Bitcoin indeed halves, does the value of Bitcoin also go up to compensate for smaller reward for mining?
Your comments are most appreciated!