I'm afraid I think it would be, yes.
my sister is so desperate to move from her rough area she's looking at a bridging loan for an over priced new build and then saying she will get the current place sold after. She's lived in the current place more than 20 years so I appreciate that any money is profit when you bought for the amount she did (she bought 10 years before I did).
but, I think she will have massively overpaid for a new build box and live to regret that. I suppose if you are okay with it going down in price, it's different. she is saying that she is so desperate to move, she will take that risk, but in reality she thinks London prices will get higher, whereas I think they must be at tipping point.
the other factor is how you feel about work? I think this is key - hate working, she loves it. So if I overpaid for a home I wouldn't think "ah well, such is life" - I would be aware of every minute I'd wished myself out of the office while paying that extra.
Unless you are in a really tough spot, I don't think I'd move. Also, is there a name for this - what's the percentage potential for you if you are moving somewhere bigger? For the sake of easy maths, if I tried to move to a large 2 bed with a separate kitchen, that extra space (which probably doesn't amount to much in sq feet) would honestly cost me about £80k.
If prices drop, yes, I will sell my place for less, but then if the extra space i want costs me £20k, it will still work out better than if I moved now.
It may be that you don't resent the extra money at all in which case....I've waffled on for no reason, sorry!! lol.