Nobody seems to be able to answer about WTF would the Russians do with the Baltic states or other places if they invaded, there is not exactly a requirement for additional land.
After Crimea, eastern Ukraine and Georgia, none of which are particularly 'useful', I rather think that the burden is on you (and those who think like you) to explain why Russia wouldn't do the same to the Baltic states if they weren't in NATO or if the alliance had ceased to exist.
'NATO shouldn't have expanded eastward' is not a useful answer, given that we are where we are.