That's easy to answer. You wouldn't convert your dollars to bitcoins because bitcoin will only appreciate in value if it becomes an important instrument of commerce; it has no other value even in theory. If you believe the deflationary attribute of bitcoin will cause it to be hoarded instead of used as a tool of commerce, you also believe that hoarding bitcoin is irrational, because the system is eventually going to collapse.

It doesn't take any insight about bitcoin to arrive at that conclusion ("deflationary currencies are unusable, therefore don't bother hoarding bitcoin"); it's just logic.