Haha, I feel similar, I was really mad for a while that he just gave in, but at the same time, I think he did what he thought was best for the country at the time, Trump was and will be terrible for the country, and if the DNC was going to fuck over Bernie and he thought he couldn't possibly win third party and if he DID fight that fight, Trump would assuredly have won.
Of course in hindsight, he won anyway so it would have been better to take the fight to the DNC then.
You really think Trump outspent Harris? You'd be wrong, go look at the data, trump just went on spaces "normal" people listen, such as podcasts, where Harris didn't.
He spoke about how America is broken, he gave incorrect reasons why, and is lying about helping people with his policies, but he didn't lie and tell people everything is fine like the dems