Too late to buy, Slack is such old news now and their market is super saturated. This could have been a decent decision several years ago, but not now.
Although the search data would indicate Slack is still super hot - I tend to agree (anecdotally) that the market is saturated, first movers have already ... moved, and most likely growth will be slow.
So far of course Slack is still much more popular among business users, but I've anecdotally noticed a big surge in Discord usage among consumers (on Reddit especially).