It’s not uncommon at all for growing companies to invest and otherwise use up any profit they generate so the balance sheet stays negative while the company keeps growing in value.
That's absolutely true. But what exactly has Reddit been expanding into? Its not like they've got AWS like Amazon or they're rapidly expanding their infrastructure footprint like NextEra or some novel product like OpenAI.
As far as I can tell, the company's biggest primary expense is administrative overhead. Not exactly value-add.