The problem with such logic is that it is not only you who mines bitcoins. Though a feeling of being involved at issuing "money" can inflate one's ego somewhat, I doubt it will be enough to actually go and try to stabilize bitcoin exchange value (since you would inevitably incur losses on yourself). If what you say were true, it would have been done so long ago by those who have big wallets. If they haven't already done this, why should they do it right now or later?
I'm confident that there are many miners already doing this, include me (maybe even some mining companies). And it does not incur any loss, that's the reason after each bitcoin hype, it crashed to a new higher low
For example, I have sold 10 coins with an average price of $800, received $8000. Now if bitcoin price crashed to $400, I need only $4000 to buy back all the coins I sold, thus there will be no net sell pressure from me and I still made $4000. I can even spend $6000 to buy 15 coins thus both of my bitcoin holding and fiat money holding increased after the crash
Sorry, but this doesn't work that way. If you sell something dear and then buy cheap, it is called speculation. If you sold some coins at $800 and received $8000 in return and bitcoin price then crashed to $400, it means that some poor wretch has lost $4000. I just can't fathom how this could possibly be called support for bitcoin price...