They had vertical integration and made bank. Then each layer got more complex as computing became mainstream, and IBM got out-competed on everyone of them by specialized companies. And then they sold them off. The only layer that remains is the most strategic: the customer relationship.
IBM is now just a consultancy.
I think that's a little simplistic/reductive.
In some areas IBM still holds if not a technological advantage at least the first among equals position, they just aren't areas that are flashy or generally known outside of folks like us - Mainframes and related technologies for example, the IBM Z series is still a huge player there.
They are also a consultancy though.
They still produce the mainframe hardware ranges though.
> IBM is now just a consultancy.
Except that they own Red Hat
Not much is left of the great IBM, but their Z architecture is still superior when it comes to reliability at scale.
In fact, "what happened to IBM?", they were in the news recently: https://wccftech.com/ibm-worlds-first-dual-architecture-proc...
Creating the world's first dual instruction set CPU.