The perception of margin is very, very wrong. Margin is the profit made after tax and on high end is generally 20-25% after tax.
with custom gear that gets reduced further.
I know of a £550 ax lightness stem where the profit after tax was 15p
That also excludes the phone call to order it which cost 30p!
The low end is where the big margins are.
cycle king and all the other stack em high sell em cheap stores will be making 50-60% on bikes sold.