Invest in DeFI, Or literally any good project. You'll never make your 6K back in time if you're just starting now. GPU, PSU, and other Hardware prices are through the roof. During Bullmarkets you DO NOT BUILD mining rigs. You buy the coin which will make you'll more money in a month than a mining rig will paying itself back. That's my personal opinion. I'm a big miner, but I started during the first bullmarket in 2017 and never stopped even during the bear market of 2018-20.
With ETH finally getting Phase 0 and moving to phase 1.5 in 2021/22 Personally the mining game's over now. On top of that ASIC on ETH that are insanely powerful are coming online this year.
Here we are again, people are packing 40 pieces of graphic cards right in front of me in a store to mine Ethereum and you are here saying you can't make your ROI back? It only takes 4 month to get ROI back on a single gtx1660 super today, since you said you build your rig in 2017? Good, my question is did you make back your ROI or NoT?