The asking price is not the same as the value.
Asking prices are set by sellers, often with optimism built in. Estate agents are instructed to achieve the best price for their client. That is their job.
Your job as the buyer is to know whether the property actually supports what you are being asked to pay. Most buyers do not have that information. They rely on gut feel, the portal listing, or a quick Rightmove search.
That is how buyers overpay.
A few thousand pounds overpaid is not just money left on the table. It is a higher mortgage balance, a harder remortgage, and a more difficult exit if circumstances change.