Changing the hashrate does nothing to supply, it certainly does not inflate or deflate supply.The amount of supply generated each day / week / month does not change when there is lower or higher hashrate.
With regards to the market : the market punishes most Altcoins at this stage, not just Dash and it does not exclude PoW coins like Bitcoin Cash or Zcash either.
If the market really values competitive mining over less competitive mining, then it would have valued PoW coins like Bitcoin Cash and Zcash higher. Instead they have the exact same price performance as Dash.
You're right. Many altcoins are at the bottom right now. But it won't always be that way. Dash is a very promising and lively project. I believe in the success of this cryptocurrency!