To sell to the public requires someone willing to purchase the shares first. That's how the market works. If someone invests in Slack despite the conitnued loss

To sell to the public requires someone willing to purchase the shares first. That's how the market works. If someone invests in Slack despite the conitnued losses, it means they see value in the company based on existing metrics. Barring companies from public listings based on some arbitrary numerical threshold is very unreasonable. Even more so when only the losses are emphasized in your previous comments while ignoring the revenue growth. That alone creates a very one-sided and biased view of Slack's financial situation.