It's impossible not to feel some sympathy, and probably he did feel rather bullied which is a real shame.
I think it was a sad inevitability though, as the Democrats were/still are in a real mess. Biden had very little chance of defeating Trump. He was incoherent, stuttering, unable to hold his own in the TV debates and increasingly prone to massive gaffes, such as calling Zelenskyy President Putin and Kamala Harris Vice President Trump.
It has become increasingly clear that he no longer has what it takes, sadly.