* Ecoterrorists -- I discount this mostly on the basis that they would have claimed responsibility by now.
* NATO sabotage -- this reduces strategic options for several EU countries (albeit a strategic option that isn't really being exercised and is almost universally disfavored).
* Russia sabotage -- this isn't terribly rational for Russia, but Russia has been unwilling to pursue rational options for a while. I can see someone in Russia thinking this will stoke anger in Germany (and the rest of Europe) that may create European pressure to force Ukraine to end the war (which is the most viable path I see at this point for Russia winning the war).
* Ukrainian sabotage -- pretty much the only actor for whom sabotage makes rational sense. Especially if it is a demonstration of Ukrainian cyberwarfare capabilities.
* Poor maintenance -- this strikes me as unlikely because NS1 is quite new infrastructure (2011), so it would have to be extremely substandard to have failed this quickly, and I believe most of the construction was done by European and not Russian firms, so I don't think that's at all plausible. But there may be some failure modes I'm not thinking of here.
It drives the market prices up (anything that spooks market participants will), and creates an ongoing situation that adds pressure on governments to act.
They worked together to put out a joint press release, and Biden gave a down-to-earth, rough-and-tumble speech about protecting depositors and kicking the failed executives and bad-luck shareholders to the curb, because this is "how capitalism works". It was an unusually blunt attempt to preemptively push back at the perception that this guarantee of FDIC-uninsured deposits will be branded a 'bailout'. (I predict that this attempt will fail and this will widely be perceived as a 'bailout' in casual and political discourse, which is the exact forum at which they've aimed this message.)
After 2008, the public gained awareness of the consolidation -- both forced and emergent -- that occurs in response to these sorts of crises. Public opinion views these outcomes unfavorably, because they seem unfair and irreversible, albeit no palatable alternatives have emerged that are acceptable to both to the public and government and industry incumbents.
[1] https://apnews.com/article/silicon-valley-bank-failure-depos...