thinking to get ROI instantly in mining is not the things that can easy to get in crypto, it is like you punching the moon while you are step in the ground. meaning at this current rate, the price of eth is not worth to invest in but to mine, because anytime the price of eth can rise while you mining it, and the cost is just the rigs that you have unlike in investment that the cost/money is in the coins and not in your own hand. if you already have a rigs before, of course yes, it is still profitable to mine eth.
The profitable mining rigs could possibly give you bigger earnings, but if you do it with eth holdings I guess you wouldn't wonder for capitalization for mining. You need to have enough buffer to reach your mining being operational.