US trip and speaking at a conference on ESTA

[lemonsoled]

I have a valid ESTA for the US from a previous trip (holiday). I've been invited to be a speaker at an event (work-related) for which I'm being paid. I was intending to go on a holiday anyway, to a different part, but since this came up I thought I'll bundle it together and do them both. The speaking is only on one day, the rest of the trip is holiday. Can I still go on my ESTA?

XH used to do work trips to the US a lot (worked for a large US multinational in the UK) and always went on an ESTA. So am I OK with an ESTA? Does this mean I shouldn't mention the speaking event? Also, why are US airport officials so rude and aggressive, I'm scared of them!

Hi @ForDeftBeaker did you have to pay to find this out? Around how much please, just to know for next time.

For anyone who asked, I did not take a work visa in the end. I did rearrange the terms slightly with work so that I didn't need one. The official at the airport was very nice though and didn't ask me anything.