i am surprised with the topic and more informed by your post.
but does it mean that BTC is the only reliable crypto due to its decentralised system/setting?
This is disturbing for me because i invested in multiple crypto and looking forward to the bull season.
Perhaps i might need to sell off my altcoin and buy just BTC? or what do you think?
You do you, but BTC appreciates time the most and is the most stable coin on the market.
You need to plan what you are going to do in the future with your alts and whether you will sell them in small minus or plus - here, nobody would be able to get you to decide besides you and your analysis.
Be wise, analyze more, and you will be happy with the results.