While I can understand your perspective, it's one of those unfortunate cases where ideology clashes with reality.
Yes, Trump never planned on following through on actually helping people. He lied, and people bought it. And yet it's no ones fault Harris's that she decided to tell people "things won't change if you vote for me".
A nation of voters isn't made up of individuals who you can convince, it's a crowd of people following certain dynamics, just like any other large grouping of things. You can either accept that and work with this fact to steer the crowd, or you can ignore this fact and lose because you're trying to go against the flow. And in the end, the only people who had any meaningful control was Harris' campaign.
Imagine you're a shepherd, and your flock is running towards the edge of a cliff. Sure, you can plant your feet and say "they shouldn't run off the cliff", but the only end result will be losing all your sheep.