It isn't vague.
It's math.
And once you run the numbers, "eventually" starts looking expensive.
.
Here's the funnel
Someone searches for your service. They see the map pack – or they don't. The ones who see it call, click, or ask for directions. Some of those become paid jobs. If you're not in that map pack, you're not losing "some" traffic. You're losing the highest-intent traffic there is. Someone typing "[your service] near me" at 8pm isn't browsing. They're about to hire someone tonight.
Try this, roughly: if a few hundred people a month search for your service in your city, and the map pack eats up most of the clicks on that kind of search, you never even entered the race for most of those people. They called whoever showed up. Not whoever does the best work. Whoever showed up.
Your real numbers move depending on your service and your city. The shape of the problem doesn't: every month you're not ranking is a month of jobs handed to someone else by default, not because they earned it.
That's why ranking work isn't a marketing nice-to-have sitting next to your budget. For a local business, it's usually the highest-return channel you have – and unlike ads, it keeps paying you back after you stop feeding it.