since DATUM became available, economics of buying hashrate has improved marginally by removing some of the opacity in pooled mining. rather than keep track of work/shares on a pool's dashboard (trusting them), users can figure out reward splits on their own from their own block templates. previously the only way to buy hashrate and minimize these arbitrary costs and risk was to lottery solo mine but not enough legitimate hashpower has ever been available to consistently find rewards so that hashrate went to larger pools instead. Cloud Mining scams basically sat in the middle between hashers and pools, it never made sense because those services add an arbitrary cost on top of pool fees. The opportunity for the scams come from preying on customers who dont know how to check if they got what they paid for. (and some of those scams never actually mined)
