It's irrelevant what the hashrate has been, there are a plethora of reasons for it, not the least of which is speculation for future gains. It is straightforwar

It's irrelevant what the hashrate has been, there are a plethora of reasons for it, not the least of which is speculation for future gains. It is straightforward logic that if there comes a time when total compensation for mining is lower than today, then there will certainly, eventually, be less mining, and therefore a less secure blockchain (but possibly still secure enough). If at the time equal security was demanded there would be no choice but to raise fees to incentivise equal mining. But this whole small transaction dream is a foregone conclusion. Even now it's clear that Bitcoin works best with fewer, larger, higher fee transactions. Miner compensation is one reason, but there are many: blockchain size, centralization, latency, etc. PoW blockchains are clearly suited as settlement layers.