the bolded part is just FUD that is being spread by some idiots on the internet thinking if they repeat some bullshit about how bitcoin is ded, dying, falling,... enough times price may go down to where they panic sold so that they can recover from the big mistake them made!

as for selling bitcoin or altcoins or tokens it is always up to you. if you see a future for any of them then hold on to them and if you don't then sell but whatever decision you end up making you have to accept the result of it too.
i for one don't see any potential in any altcoin, specially not in tokens so i don't even hold them in first place to want to sell or not. but i see a huge potential in bitcoin so i am going to continue investing more and more in it each time price falls.