UK Tech Sales: Does anyone actually do well out of events like DTX & EdTech?

Seems like you pay 10~20k for a stand, the foot traffic take the freebies and forget all about you 3 days later.

My first thought was that we need to do better on our end but after speaking to multiple other vendors everyone says the same thing - these events are a trap.

Does anyone do well and if so who do you sell to and why do you think it works?