Somebody said somewhere that the only rule in networking was that "Ethernet wins". Looking back that certainly seems to be the case and today you wouldn't bet against it. Those who did in the past have lived to regret it.

IBM was an early casualty. Back in about 1982/3 or so it introduced something called Token Ring and it orchestrated a 'buzz' against Ethernet declaring it inefficient and non-deterministic. Didn't matter. Ethernet sailed on and Token Ring eventually bit the dust.

And so to 1990s when they all said putting Ethernet on unshielded twisted pair was a bad idea. In fact some said it was impossible. Switched Ethernet promptly became the standard for data with structured cabling.

By the late 1990s Ethernet went everywhere and did it at 100 Mbit/s. By this time asynchronous transfer mode (ATM) became the preferred data switching standard in telco networks. It was needed to keep up with the speeds offered by fibre as clearly packet-based switch/routers weren't up to it.

Of course they were. Again, the impossible took place and Gigabit Ethernet triumphed while ATM switches and networks fell away.

More recently we have Carrier Ethernet and of course, WiFi (radio Ethernet).

Why has it done so well? Simply because it's become a simple format for data packets. Simple can scale and adapt, simple can be made backward compatible, simple is more cost-effective to iterate in small steps, so simple wins.

I peronally don't think it will ever go away.