I thought Putin would not ultimately invade since the cost would be significant for Russia and destroy any favorable views some Ukrainians might have had.

It could be that the order to attack wasn't really planned. Putin doesn't seem to be the impulsive type, but maybe something happened.

Although Russia did warn that it was ready to initiate a war. The real analysts the should get credibility are those that said that war with Russia is becoming more probable for a few decades now. Short term prediction like that he would attack in three month are nothing more than bets in my opinion. It does not infer credibility or knowledge.