Eventually, as usage increases (and I think it will thanks to XMR.to), people that want to buy something privately will maybe buy 50$ worth of XMR even though their purchase only requires 40$ worth. Sure, this is one person now with 10 XMR off the markets, decreasing supply by a tiny tiny fraction, but this will add up, over time.
And further to make speculation of XMR even more difficult, is that the price of XMR doesn't matter for this use case. If I need to buy 50$ worth of XMR to make a private transaction, it doesn't matter if 50$ buys my 150 XMR or if it buys me 0.001 XMR.
When it comes to the idea of price of Monero goes up if it gets more transactional use, this is false statement.
Here is very simple reasoning: You convert 50 usd to xmr and spend them and the merchant dumps the coins back to market => the effect is more or less neutral.
If the merchant keeps the coins and do not dump them, then it is obviously very bullish especially if there are lot more merchants deciding to hodl.
Hodling is the only thing which gives a value for a coin. Without hodling the coin serves a mere token and cannot reach any significiant prices.
The latter part of your message is true - indeed it doesn't matter if you get 0.001 XMR or 150 with 50 usd.
Monero will rise in price only and only if more new people enter to the markets long time enough.
The time would at least be the time the of the average bitcoin transaction - if you were using xmr.to. If you do simple "on the back of a napkin" calculations, of how much of the (xmr & btc) monetary mass would be removed from the market at all times, it's not insignificant.
It isn't insignificant but really the bigger factor for use-in-commerce is just that people won't instantly and constantly convert, for convenience reasons if nothing else. If you know you are going to make another purchase tomorrow or the next day or even next week you will just keep the coins. Even in an environment (not now) when short term interest rates are significant, people don't put all their spending money into interest-bearing accounts; they still hold on to some cash.
We're a long way from use-in-commerce being significant enough to matter though. BTC isn't there and BTC is about 700 times bigger than XMR.
