The Big Lie Provides Catharsis.

Probably because nobody thought trump could win.
Hillary literally spent the entire campaign with an entitlement mentality and almost 100% of the media and politivians backed her up.
Pride cometh before a fall etc

Exactly their arrogance prevented them seeing the growing revolution

I knew there would be an excuse. So, Hilary wasn't "corrupt," after all?

You asked for an explanation so I'm giving you a possible one.
Hillary was an established politician with an ex president husband that people (inexplicably) liked and had the full support of almost every politically active corporation and 100s of millions of campaign spending money. President Trump was a celebrity who was attacked on day 1.

This time around trump was a president going for a second term with more support than the first time rivaling an 80 year old man who often struggled to string a full sentence together -- I assume a different situation would lead to different behaviour.
Of course nobody really knows that did or didn't happen behind closed doors in 2016, nobody was looking.

They tried. Hillary stole at least 5 states, but Trump swung several states that were traditionally blue, totally caught them unawares.

Why would Hilary seal some states and not the others she needed to win? That doesn't' make sense. Nobody knows what happened behind closed doors, in either election. But, we do know that basically honest people from both major political parties staged elections in all 50-states and the territories. In 2016 Trump won the states he needed to win the presidency. In 2020 Biden won the states needed and got over 7-million votes more than Trump.

The courts, all the way up to the top agree that evidence to the contrary has not been presented. Trump lost. It is that simple. A lawful and peaceful transfer of power on January 20, 2021, is his only appropriate option.