Is Sanders staying in the race because he thinks that Biden will crash by convention time?

He's staying in because (1) he is running to be the nominee with being president as his goal and dropping out would not serve that goal, (2) he's invested a hell of a lot of time and money into his campaign and has not yet been ruled out as winner by the delegate count (ie. it's not a runaway majority for Biden yet), and (3) he believes his campaign platform and plans are superior to Biden's, while Biden's would just be a return to the status quo that led to enough people wanting Trump for president to make that happen in the last election.

Why wouldn't he stay in?  It's not his money that he's spending to stay in the race.  

Biden's mental capacities are diminishing fast.

Biden is sure to crash the next debate.

I hope he has a shot. Truth is, the evil industrialist mofos that own and rule this world are unlikely to let someone like Bernie Sanders ever become a President.

Sanders will destroy Biden in a debate, I guess he's hoping people will notice in the age of stupid