I'd say the very fact that most Bitcoins weren't created in the first few hours is a good indicator that there are no time travellers. Or if travellers do exist

I'd say the very fact that most Bitcoins weren't created in the first few hours is a good indicator that there are no time travellers. Or if travellers do exist, access to time travel has been restricted, or perhaps Bitcoins and possibly even currency is not of interest in the future. In fact, time travel could render investments obsolete.