He didn't invest much time, just the time on the call and the time to determine it wasn't a fit. So I wouldn't call it optimizing for lottery. Instead, I'd call it optimizing for reputation. And you can't know what doors your reputation will open for you. You just can't.
What's the alternative? If he'd fibbed and tried to make it work, and then wasted everyone's time during the sales process. Or worse had an unhappy team at the end of the POC or a contract that the company wouldn't renew?
I guess he could have not taken the call, but I think if a client asks you to do that and it isn't invasive in terms of effort, most consulting folks would do it.
There's other low-but-non-zero probability outcomes with a high payoff out of such a call, too. For instance, it may turn out that you are a good fit, because the requirements got mangled during the inevitable game of telephone. There's enough such possibilities that it's worth taking the call, but also not wasting anyone's time once the situation has become clear.
Another one I encounter frequently ... it isn't a good fit for this team, but seems like it might be for $PeerDepartment. And now you have a warm introduction from someone they trust.
Also some high-probability relatively low payoff events. The OP could probably expect the hedge fund that took the meeting would feed back to the bank that referred them that they appreciated the introduction and thought the team had integrity and good sector-specific knowledge. That might help cement relations with the existing client and win more referrals for the company.
And hedge fund employees impressed by a presentation are likely to talk to and occasionally move to work at banks. The headhunting relative with the ideal job vacancy certainly wasn't the most likely of the many potential positive outcomes!
What's the alternative? If he'd fibbed and tried to make it work, and then wasted everyone's time during the sales process. Or worse had an unhappy team at the end of the POC or a contract that the company wouldn't renew?
I guess he could have not taken the call, but I think if a client asks you to do that and it isn't invasive in terms of effort, most consulting folks would do it.