Why would people donate riches to the church? You say in honour of God or whatever. Since when did God need any of these things the only way people would do this is if they were told to do so.
Have a look in Exodus Chapter 25 and afterwards - WHO is it who told Moses to gather together huge quantities of gold, silver, precious spices and other rich materials for use in the building of the Dwelling Tent and the Ark of the Covenant - and for the rituals which were to take place there? No man told Moses to do this, but God Himself.
Take a look in Leviticus - WHO is it who decreed that the animals used in Temple sacrifice had to be the best of their kind - with no blemishes of any kind? WHO decreed likewise that no man who a deformity of his person could serve as a priest (ie that the MEN who served Him also had to be the best of their kind)? Again, no man but God.
Take a look in the New Testament - WHO rebuked Judas for complaining, as you are doing, when precious ointment was ‘wasted’ by being poured on Jesus’ feet? No mere man, but Jesus Himself - God Himself - said that the woman who poured expensive ointment on Him was doing a good thing and honouring Him.
God doesn’t just ask, but demands (as He has every right to do, being God) that we offer of our best to Him.
You’re right about one thing, He probably doesn’t need it. Neither, probably, does He need us to gather on Sundays and worship Him, after all He has angels to offer constant worship to Him. Yet He still commands us to do so.
He institutes these commands for OUR sake, because when we do these things they remind us to give Him first place in our hearts and lives. They remind us that all our gold and silver, not to mention our bodily health, our time, our life itself, all come as precious gifts from Him. It teaches us not to become too proud of our material possessions or so attached to them that we are unable to part with them.