Don't sell all your bitcoin at this time that will be such a big regret in your life eventually that you'll really hit yourself.
Bitcoins will be going up in value still for years and years selling them now without the need of quick money is just a big waste if you ask me.
Selling all your coins at once is indeed not a good idea, but there is nothing wrong with people securing profits. Especially since it gives you an extra bit of fiat that you can use in case the price goes down again. It's all about increasing our coin count, and that's a smart way to do it since the price always tends to go down after spikes.