I see some layers to it in my view:
- nostr's lightning bias pushing away users of other cryptocurrencies while the wider Bitcoin bias pushes away dollarbrains, concentrating a certain group of people here
- feeds that boost zapped content
- people who give follows, likes, replies, and reposts to high zap amount npubs, hoping for zaps
- villains who use zaps to promote their own unfair bias willingly
- paid relays and other spam suppression methods that unfairly benefit lightning users or those with more money in general