To the extent the security situation has deteriorated, it has deteriorated because of a continuation of the same situation that made them join NATO. They'd not be in any better position without it.
Ukraine was neutral until Russia invaded it. I guess Sweden and Finland saw that and figured relying on being neutral didn't work so good.
Dunno if the Swedes are "short sighted and brainwashed" so much as familiar with Russia's centuries of aggression and invasion?
EDIT: crazybonkersai: Your comment below has been flagged (not by me), so I'll reply here: At no point have I suggested there is nothing strategic about Putins decisions - that is entirely a strawman. That does not mean there isn't reason for neighbours to be concerned for their safety. A full scale invasion of Finland or Sweden would've been unlikely even without NATO membership (not least given how Finland did last time), but Russia has an extensive and recent history of testing and probing the readiness of their neighbours, and not being concerned about infringing on their sovereignty if they believe it serves their other interests. The more likely scenario affecting Finland and Sweden would be if Putin decided he wanted to attempt going into the Baltic states, and saw a need to impose control over the Baltic Sea as part of the process.