I think it can be measured, but if we got to that point, are we even human beings and not just organic, robots? I think this plays into what kind of "culture" are you trying to cultivate. Culture is a very hard thing to measure as well.

My old accounting professor use to say, "You get what you measure".

Can't you measure culture by your company employee retention rate quarter over quarter or year over year?

You can have a terrible culture among people who are locked in by illiquid equity or the inability to get hired anywhere else.

You can have a great culture among people with a high propensity to want to try new and different things every few years.

The problem is entirely short term thinking with precise measuring can also lead to bankruptcy by not understanding how the rest of the world is changing, missing out on an idea that sparks a whole new business division, all of this other 'stuff' that's hard to measure. In general I think the point is being a miser is not going to lead to great success or new ideas and ways of doing things.

Your employees could quit when they get other offers from businesses that care about professional development. You will have higher turnover and institutional knowledge will constantly be leaving and having to be relearned. Onboarding new employees more often has a direct, measurable cost but is obviously different for every business and position.

Your employees could learn advantageous and/or competitive information from talking with people at the conference. They will bring this back to you and ask for a raise when it turns out it's a bonus for everyone, but that's what we want, right? Maybe it's important enough that you get to pitch the new thing to the CEO and you get a raise as well. Everybody wins.

This really doesn't have anything to do with what the person you replied to said. He merely asked for some sort of cost/benefit deal, rather than handwaving away the analysis.

And I plainly told him that conferences are a perk and perks play into job decisions and that there is a direct cost to losing your employees.