Ok, let me state it more plainly then. If you changed the reward ratio from 60/40 to 20/80 (or 8/92 - the sweet spot?), which masternode owners do you suppose would not dump their coins within the hour of finding out? What would that massive influx of supply do to the price?
None of them would (if they had any sense). Clearly that's the whole point of making this argument - that it's in their interests to support this. You're over-focused on the reward. Masternodes are far more exposed to capital losses (or opportunity cost capital losses) than they are to small changes in reward because they have 1000 Dash at stake.
What would be the difference ? We'd be going from 1.3 Dash per week (45% reward share) to around 8% (0.23 Dash per week). So you'd be making 1 Dash per month for running a node.
Now that is far more realistic at high valuations. It's also far more realistic given the operating costs that nodes incur. It also highly incentivises the investment in nodes because the operating profit margin of a masternode (unlike with BTC/LTC et al)
increases with increasing Dash price, but the real objective is not increased reward anyway. It's capital gain of the holding (and therefore EVERY Dash holding, not just masternodes).
At the moment, everybody is paying for masternode rewards. Not only masternodes themselves (through relative capital loss compared to full mined coins) but also other holders who don't receive any reward. If you really think all this is worth it just to sustain the illusion of a numerically consistent but otherwise diminishing reward, then I don't think you understand your own investment.