If a wedding was no more than a nice seuda, without everything else, a lot more people would be able to afford it.
There are more costs to the wedding beyond the public events (vort, wedding, sheva brochos, etc.).
Gifts (not extravagant, but basic Seforim, clothing, jewelry, shaitel, etc.), and basic housing expenses (furniture, appliances and dishes, etc., as well as help with housing expenses depending on local custom).
Those things add up.