Even my young kids understand that money is finite and if I spend on X I wont have to spend on Y for them. There are things I get them because they want it or they asked nicely but not because of peer pressure.
If I buy them everything their classmates have...
I dont teach them the value of a dollar
I teach them that peer pressure is what is important. Fitting in is the most important thing.
I teach them that they get everything they want which can spoil kids.
They dont value what they have. When they get a few items on their birthday they dont play with each one as much as much as if the ones they got unexpectedly.