Does it feel nicely safe at the time they are arriving and waiting?Euston is warm and dry and is not unsafe. There's plenty of seating dotted around, in particular on and under the mezzanine and in the area that used to be the independent newsagent near P12. There are also bars etc.
I never understand why people collect in that manky area by the toilets. I think the intention of it is that people can sit there and wait while e.g. their kids use the loo, but as you say people use it as a waiting room and it's a right pain when they do.
Quoting @Meerkat (sorry, the header didn't work properly):
The only seating on a platform at Euston is on 8-11. This is just people picking a really strange area of the station to sit and wait, outside the stinking toilets on seats intended for short term occupation while children/partner/whoever uses the loo.
I would guess the paranoia about being in the right place at the right time for an expensive one off train means they want to be on/near the platform, particularly if they have luggage. And there is a natural instinct to get as near to your destination and then look for where to wait. They may also have seen that there is a Sleeper lounge (on a map or website) without realising it isnt for the plebs.
