Alpha != Itanium
Alpha had several problems that precluded its adoption as a mainstream ISA.
The first was power, and DEC ended up choosing the winner themselves.
https://en.wikipedia.org/wiki/StrongARM
"According to Allen Baum, the StrongARM traces its history to attempts to make a low-power version of the DEC Alpha, which DEC's engineers quickly concluded was not possible."
The second was the weak memory barriers.
https://redvice.org/2021/memory-barriers-alpha/
"Of relevance to this piece, however, is Alpha’s exceedingly lax memory model. Unlike ARM, which will respect data dependencies for reordering, Alpha can reorder reads regardless. This is really hard to reason about, even for people comfortable with lock-free programming."
The third was their own software licensing, which was outrageously expensive.
An AIX license for a single user was included in an RS/6000 purchase (participated in a 43p purchase in the mid-90s), while OSF/1 was over $40k, ruling the Alpha out. Third-party Alpha resellers with beta versions of Linux and Windows were not sufficient to overcome this.
ARM definitely deserved to be the survivor.