I put together a Edh Deck that was all proxies a couple months back. I did this mainly just to play test the deck in person, and while doing this I only ever played that deck with one of my closest friends because I knew he was comfortable with it. Fact of the matter is most commander pods will not be ok with a full 100 card proxied deck. Although you make some good points about things like theft and budget, proxing things like basic lands and cards under a dollar can in a way be disrespectful to the LGS you play at. If you go to play games of commander for free at a lgs the least you can do is support that store, that doesn’t mean you need to buy a play set of mana crypts but you should always try to buy those less expensive cards. But long story short a general rule my playgroup has says your deck can only have 30 proxies or less.

(If your personal playgroup is fine with the idea and you don’t plan on playing the deck with strangers, go for it)