In a way it was their undoing. BlackBerry never managed to think of phones as more than communications devices.
But I don't think the company realised how much smartphones were surpassing them, so they were very late to move to a smartphone platform. When they did, it was to QNX – the basis of BB10 – and it was a very good OS, but it was too late.
It reminds me of Palm and PalmOS. When it became clear that they needed to move to ARM, they talked to Symbian about using it as the basis of the new ARM PalmOS. That would have been a killer platform – but they didn't do it.
https://www.theregister.com/2000/11/14/palm_cto_rubbishes_30...
The company decided against an absolutely superb option which would have given them a major technological advantage.
Instead, the replaced their bought-in 68K kernel Kadak AMX, which actually did multitasking but Palm didn't pay for that option (!) – with their own emulator thing, MCK, meaning that ARM PalmOS (PalmOS 5 "Garnet") was still single-tasking with almost no multimedia support.
Then PalmSource bought the remnants of Be, using it to make PalmOS 6, "Cobalt".
https://www.mobileread.com/forums/showthread.php?t=18956
I read a lot about Cobalt and it looked amazing for 2003-2004. But nobody shipped phones with it – not even Palm itself. Instead, they... licensed Windows CE.
A second disastrously bad decision. Few companies survive their first, but Palm did it and survived long enough to do it again.
"don't fix what works and bring money"
...until someone comes and disrupts you and all the assumptions that keeps up your business