just by buying wedding stuff tens of millions of gil vanish from every server every day

I dont know how many gil are generated per day but I'ld say just because of the wedding npc the servers are going to lose more money than they generate each day, which works pretty well against an inflation

If you need money or materia: start desynthing the stuff yourself. If I invest 2m gil in wedding gear (which takes about 30 min) I usually make 5m by selling the demi III (~42k), hard leather (30k) and HQ leather (50k)

you can also use the leathers to craft ilvl 70 dow gear and bind it in 4-5 t4 runs, the grade IV materia rate from ilvl 70 stuff is ~40% and you still have the chances to get allagan leather + silks which also sell for a lot