Why would a password manager need $1B?

Cloud password manager functionality can be accomplished in 6U of server space. Vault files are measured in kilobytes or megabytes, millions of customers could be handled by a single SSD RAID and a fast Xeon. Infrastructure and software to make it secure, reliable, and user friendly, add expense but not 9 digits of it.

They are moving into enterprise(or trying to anyway), see things like passage[0], etc. They are trying to grow their brand and reach beyond just a simple(but nice) password manager.

0: https://passage.1password.com

I do realize that Bitwarden has also taken funding, but nowhere near this much. That being said I'm always baffled by some talking heads in the security space who continuously hock 1Password. I'm sorry, but when you've taken that amount of funding - the customer is no longer the customer, the investors are and that is who is being catered to. Does the industry as a whole not remember LastPass and the garbage that has become to cater to "Enterprise"? I would bet good money that I can come back to this post in less than 10 years and highlight the downfall of how 1Password has changed hands, changed direction and the product has become less than ideal or a leader in their space. The upside with Bitwarden is it can be forked and kept true to it's roots. I get it, 1Password has a few things that work slightly better - but I'm forced to use it for work and despise it's bloated feel comparative to Bitwarden.

I would be more interested in knowing why would a password manager _get_ $1B.

My mental model of that situ is "money chasing eyeballs" since having a curated list of folks to market to is the value - it's all about the user list

Because storage, even globally replicated, isn't the core cost or the core function of a security company.

Your app, the detection of forms (when total idiots try to prevent password managers being used), the security audits, active intrusion detection, etc... those are yet to be handled by an AI, so these cost a lot.