Comment by hnav

Huge asymmetries both in bandwidth and capability between up and downstream. A lot of US users are still on DOCSIS, a lot of users worldwide behind CGNAT (less of an issue with IPv6), stateful firewalls for cellular to avoid creating unsolicited radio traffic. A ton of the bandwidth the average person is consuming is from talking to a caching box sitting in the ISP's DC. Basically the network you're connected to is optimized for feeding you lots of data and having you send back ACKs.