The total number of bitcoins in circulation is capped, even though the total quantity of wealth in the world continues to increase.
If bitcoins were the only currency used, then yes, this would cause hoarding problems. Does this mean bitcoins are flawed?
No. It just means that there is a cap on how much wealth can be purchased with bitcoins.
In other words, prices of goods (in bitcoins) will (eventually) stop deflating, even though there is a fixed quantity of bitcoins, because other cryptocurrencies will be introduced.
Should everyone be allowed to use these public services when not everyone is donating? Should you be allowed to use the police even if you haven't been donating to their budget? What if the police have two calls: one from someone who has donated and one from someone who hasn't? Who has priority?
The tax system exists to fund services that are generally not used by someone until they are needed (FEMA, Medicare, unemployment, etc.). I can honestly say I would never pay into any of these programs unless I had to and I think most people would do the same (even if they wouldn't admit to it openly).
