buy into sth

buy into sth (believe, agree with) — поверить, повестись
buy it

Examples:
I don’t buy into the idea that there are no ghosts. I’ve seen one!

A: This time I am going to finish the whole 26.2 miles marathon.
B: You said that before, but I don't buy it.

I don’t buy into the idea that ~ меня не проведешь, я не куплюсь на это, не попадусь на эту удочку (контекст)

[попасться на удочку]
rise to the bait
[hook, line and sinker]
[fall for it]