but the odds that I and others even reached one with an already used balance proves that private key collision is a common occurrence even given the trillions to 1 odds.
Yeah it can happens but it's not common (how do you define common btw?).
Phishing give you better odds than looking for private key. But for sure if it's just for fun, let's try to find an address with 0.11111 BTC in it!