As for IBM, its market cap is quite close to Microsoft, so I think they did reasonably well (they could have done even better if they've bet on software earlier, but that doesn't mean they should necessarily "bet outside their walls"). Also, the fact that they invested everything they had on an "open" platform (the PC architecture) is kind of an agreement to what you said they should have done... No? As for Twitter,…
IBM now makes most of its money through consulting, software services, and enterprise hardware and software.