Do bigger salaries drag it up making it look unrealistic to most?
If it were the mean then, yes, that could happen. But average wage figures are based on the median.
If you line everybody up from the lowest paid at one end to the highest paid at the other then then the median is the person in the middle of the line so a few millionaires at one end of the scale won't distort the figures.
Also, don't forget that this is only for people working full time and excludes part time workers.
The actual figure according to the ONS is £569 pw or £29,588 per year. They have a resource here:-
Employee earnings in the UK: 2018
where you can find average figures for all different parts of the country split by local authority (it's about halfway down the page Figure 9)
The highest paid is the City of London (average £1,054 pw) and the lowest is Rother (Bexhill on Sea) with an average of £427 pw.
A bit further down the page they also break it out by occupation so, for example, butchers earn an average of £412 pw (£21,420), educational support assistants earn an average £304 pw (£15,840) and accountants earn an average of £764pw or £39,730.
Just to demonstrate how different people view different things, I remember some time ago that there was a piece in The Guardian that the Labour shadow chancellor had mentioned that £70k a year puts people in the top 5% of earners and he wanted to raise income tax for these people.
In the BTL comments section there were so many people saying things like "Oh I make £70k a year and I'm certainly not rich, in fact we barely scrape by". These people really had no idea that the average salary was £29k and couldn't conceive of how anybody could live on such a low amount as £29k a year.