WHAT?

This makes no sense to me. Assume BTC was 10.000 and is now 300?

what?
If you buy an Xbox for 300 USD then you are down 300
If you buy an Xbox with 1BTC (worth 300 USD) and then buy 1BTC (at 300USD) then you are down 600.
FUCKING IDIOT
Let me spell it out for you.
Suppose you want to buy an Xbox which is 300 USD.
You have 300 USD in your bank account, and 5 BTC in your wallet.
Scenario 1: you pay the Xbox with dollars. You now have: 1 Xbox, 0 USD, and 5 BTC.
Scenario 2: you pay the Xbox with bitcoins, and you buy back the same amount of bitcoins (i.e. 300 USD worth) on an exchange right away. You now have: 1 Xbox, 0 USD, and 5 BTC.
See the difference in the end result? Now, which scenario do you think will help Bitcoin grow more.
Note that in either scenario, it doesn't matter how cheap or expensive you originally bought the bitcoins. It ONLY matters that you are now spending 300 USD worth of bitcoins (at today's rate) and buying back the exact same amount of bitcoins right away (which will cost you 300 USD, give or take 0.1% exchange fees maybe).
Thank you.
I thought my explanation was retard safe, but I underestimated the retard level of some people in here.