Mate the only reciepts around are that anthropic says in it's s1 that it made it's largest profit, 16 billion, last quarter. If they get their 2 trillion IPO that means it's a return on investment of 125 years. So by receipts you're just wrong about anthropic being a good investment, or like you, me, and everyone else in this thread we can speculate based on current and possible market conditions about what happens in the future and whether people will think Anthropics a good enough investment after the IPO to make people pay more to buy the shares.
To your example of open source not eating Offices lunch how about I point out linux verses unix, or MS visual sourcesafe vs git, commercial web servers vs apache/nginx, commercial PBXs vs Asterix?
edit: I just realised that all of those examples were for more technical software (with the possible exception of linux). So things to also consider: does anthropic win in the more technical space against open weight? does it win in the less technical space against go with the flow bundled copilot?