Never bought bitcoins! However, back in 2009-2010, a client of mine paid me in bitcoins for the services I did. Had no clue about bitcoins so I though the client was a stupid prick who didn't want to pay me for the services I offered. So I didn't care and blocked that client. I did not even care about the bitcoins he sent me, because at the time the value of a bitcoin was under 10 cents.

Now, I have no idea where are those bitcoins, don't even have that email id which I used to interact with my client. I guess I did not have the luck by my side! Otherwise, I would have made millions from those bitcoins..

Anyway, still not interested to buy bitcoins and this time due to its price 

Being a millionaire in my currency, I can answer this question pretty well. So my simple answer is, the way the price of bitcoins increase and decrease there's always a remote chance that all the money I invest might get lost. I just can't trust a currency which is yet not regulated by RBI in India.
That is the only concern!