RedHat's biggest value was perhaps the disruption it caused in the OS market and the damage it inflicted on the bottom-line of the OS vendors as existed in the 90s, with the wider world benefiting from lower costs on server provision than would have otherwise been possible.
Now that most of the competitors have gone, and the general trend being a move to cloud that value was already fading - cloud vendors are full capably of building their own platforms, and on-premise is being undermined on price leading to a shrinking pool of potential customers. Yes there are other products in the line-up, but are they as mature revenue streams?
RedHat shareholders have timed this right, and got out just after the business's value has peaked.
Meanwhile IBM has repeated the mistakes we saw at HP and is in the process of blowing a fortune on an over-priced asset past its peak, while adding considerably to it's corporate debt bill. IBM shareholders have baulked at the move and may yet block the take-over. Even if it goes ahead, IBM is at high risk of a credit-ratings downgrade with consequent financial costs being another nail in the coffin.
Not to worry, all the current execs with still get their pay-offs, and lots of new Execs and BAs will be pulled-in over future years to try and fix the integration of a business with an alien corporate culture.