As I have read noone exactly can answer this question as there are 2 opposite opinions on it. Btw I think the opinion that mining is worthless is more popular than the opposite opinion.
Mining is not worthless, it supports the blockchain and secures the network. Without mining, there is no Bitcoin.
The correct question is "Is mining worthless for the home user to ROI?"
If you only have a few hundred or a grand or so to spend, yes it's worthless.
It's an arms race right now, and many of the home miners are exhausting getting new circuits installed, and you're slowly seeing a shift to the datacenter for cooling and electrical needs.
It's like the old saying "Don't bring a knife to a gun fight". Biggest and most power efficient Asics win. Unfortunately, it costs significant amounts to keep up.
Data center hosting fees are going to eat profits very shortly. They are already over 10% of miner earnings and the growth of difficulty will bring it over 100% by the end of summer. The smart folks are offering hosting contracts. Once the rent exceeds earnings, they will get free miners. Even if the only value is as scrap, they win.
It used to be easy to calculate the days to break even on a miner and make a decision to buy or not. But now, power, network and labor are significant chunks of earnings and dramatically extend the time to break even. Another down leg in the BTC exchange rate will ruin many people if it comes.