it is usually called FOMO (fear of missing out).
and in any market there will always be people who make irrational rushed decisions like this. these people think of trading as a form of gambling. they think all the profit and loss they are experiencing is purely based on their luck and nothing else. they know nothing of speculation and analysis and make rather random decisions.
in bitcoin and mostly altcoins these people have a bigger portion of the market but as the market grows like bitcoin's their portion becomes smaller and with it their effect on the price.
I was also going to point out the fact that it is normally called FOMO and not really panic buying, although I suppose it can be considered as such.
Anyway, just remember that so far no one has lost money by buying the "top" in Bitcoin, although they may have had to wait some time to breakeven again. Case in point, people who bought at the absolute peak back in late 2013 probably felt pretty bummed out in 2014 and 2015, assuming they didn't sell at a loss. However, right about now anyone that managed to hold their 2013 peak purchase is probably feeling pretty good about themselves.
I am not saying this will always be the case, but so far Bitcoin has been a pretty safe bet even for those who are inclined to FOMO (panic buyers) occasionally.
Panic sellers on the other hand, it is a different story. Those who may have panic sold after the 2013-2014 crash at sub $200 levels would have had to buy back in at a loss. Same thing earlier this year when bitcoin rose above $1000 and under again, people who sold at sub $800 again had to buy in higher. No telling how high it will eventually get, and taking some profits off once in awhile is a good idea, but I wouldn't recommend playing the shorting game as in the long run it seems risky.