At $1000 per Dash the masternode network would get paid $300 MILLION per year. Can you fathom that ? Since most of it's pure profit there's a theoretical, say $100 million worth of Dash that needs to get sold just to pay tax authorities and hitting the highest tax rate bands. To me this is bonkers. This doesn't happen with mining.
Are you sure? In several jurisdictions that I know, masternode rewards are exactly like mining income, tax-wise. (i.e. earnings for services on a given network)
Also, do you imply that miners sell less frequently than masternode operators?