It's an easy mistake to make, honestly. They know exactly what they're doing, and they do a great job of pulling you in and getting that money in hand.
I've done a few of this sort of free webinar at this point because I figure, what have I got to lose? What I've found every time though is that the webinar gave nothing of any practical value--just the sales pitch, and to me, that's a red flag.
In any case, I've been automatically saved from making any of these purchases because I simply don't have that money to spend. If I did? Might've been a different story.