Slack is reportedly raising another huge $500M round of funding (techcrunch.com)

How can you be valued at $5 billion and not be a functioning business? Investors will never see that money.

I'm thinking Slack's issue is their free version is too good and the paid version is way too expensive (per user pricing gets scary) I know in my experience we don't have any trouble using free and we have too many people to make a jump to the paid. I think Slack needs a "middle ground" solution where small-medium businesses won't balk at the per user pricing.