It is worth it if you don't take a loan and dump all your money into it as a full time job. If you have a full time job and the cash to spend just do this as a hobby to make extra cash it is still worth it. The huge miners is what hurts the little guys anyways.
I didn't take a loan, but I moved almost 2 years ago so I could afford to make mining my "full time job".
It's been worth it and still is at this point - for me.
Your details and preferences may differ.
GPUs don't "go obsolete" in 3 years, even in mining usage - the HD 7870/7950/7970 from *over 5* years ago are still effective profitable miners, and the R9 290 from about 4 years back or so is STILL one of the top Ethereum miners on hashrate (only surpassed reliably by the GTX 1070, GTX 1080ti, Titans of the Pascal generation, Titan V, matched by the R9 390/390x and SOMETIMES topped by Fury and Vega cards).
If your electric cost for a GPU rig is 1/3'd of your gross income from that rig, you have high priced electric by mining standards.
Same boat, I used to dump my GPUs after a year or so but I always regretted it. I think its better to use them for 5 years at least , since they are paid off
at that point just mine coins or algos that use less power if you have to, and its all green. Plus any GPU that runs for 3 straight years with no issues is a keeper
I will probbaly never go bad, unless there is some physical damage to the fans. I cant count how many times I bough a new GPU and it died after a few months and I underclock and
undervolt all my gear. My good GPUs will never be sold.