But I don't have it and won't be replacing my Ethereum with Dot. I'll invest somehow into other coins and it's going to be part of my list where I'm going to diversify my portfolio.
If you want to have DOT, you don't need to sell your ETH. Just buy DOT with your USDT, do you still have USDT or fiats? Diversify your portfolio is a good idea, I support your decision to buy more coins. Many people also diversify their assets to optimize the chance of gaining bigger profits. I rarely saw people who suggest investing in a single coin only, even it is BTC or ETH. 