Bitcoin
While I think Bitcoin is fundamentally flawed because of the 1MB blocksize limit, there were two other things that affected the prices of cryptocurrencies today.
Coinmarketcap
Coinmarketcap.com, or whoever that owns the site decided to exclude the prices of Korean exchanges in their price calculations.
This led to some kind of panic that led people into selling their cryptos.
If you check the coinmarketcap.com site it seems like 67.000.000.000$ of market capitalization just disappeared. The other reason why Bitcoin fell today might be because of the high fees / congestion but I find this unlikely right now. Another thing could be the "Microsoft FUD".
Microsoft
As people started to notice that Microsoft dropped support for Bitcoin payments people might be finally realizing that Bitcoin failed as a currency.
For me what really stands out from the reaction of Bitcoin Core supporters and the mod from r/bitcoin is this comment here:
I've seen enough anecdotal claims that personally I'm convinced that Microsoft has indeed ceased accepting Bitcoin as payment. Maybe they goofed up again, but I doubt it. Can't say I blame them, although this is the sort of thing that should come from an official source rather than a tabloid site.
I bolded the part that I feel is important.
Can't say I blame them
I am very sorry but to me it looks like they are admitting that they failed.
Get out of their failed project while you still can, that is, if your coins are not stuck...