While the threat of an uncontrolled AI singularity seems to make a lot of sense, the main reason that makes me think it might not ever occur is that there has n

While the threat of an uncontrolled AI singularity seems to make a lot of sense, the main reason that makes me think it might not ever occur is that there has not been any sign of alien AI. The Universe has been around for millions of years, which is plenty of time for AI to develop somewhere else (probably multiple times) and in my opinion one of the key features of intelligence is exploration, which means colonizing pretty much everything. The lack of alien AI signs makes me prone to think that AI is not achievable or there is a plateau somewhere (energy-related? atom-size related?) of how smart AI can really become.