WHMCS (or another brand) or software for automating written hosting?

We are a small, established hosting company, and we have a long established in-house billing system. Unfortunately, it is not feature-rich (in fact, it's a euphemism – it's just a very little automated billing system) and customers seem to need or expect a more integrated and automated system than we are almost completely missing (customer section, order history, etc.). order, billing, support – all in one place). Most of the features that we miss have been ignored not because it would be very difficult to add solutions, but mainly because of serious security issues (we preferred to keep the system less developed, but safer, but that requires MUCH more manual work, customer expectations).

Now I see 2 options:
1. Either we continue to develop the current system until it is better aligned with customers and our own expectations.
2. We opt for WHMCS or another trading system, but we also have to customize it in depth.

In the first case, it will take a lot of time and effort, we will make a lot of mistakes and we will produce a lot of slow features, but at least that will be our mistakes and we will have a lot more control over the pace of development and published features and we would know from time to time (I read on the WHMCS forum that recently, many features have been published, but also many bugs). So these are our bugs that will drive us crazy. instead of those of WHMCS. In real terms, it would be MUCH less secure than WHMCS (as developers, we have no knowledge of security), but being our own system, used only by us (because our code would not be used by anyone else ), WHMCS would be potentially less vulnerable than globally known vulnerabilities, but it would be much more exposed to a somewhat informed attacker who would specifically target us.

What do you think? Is it worth pursuing the development of our own system, knowing that at present it is only 10% of what it should be or that we should give in and follow the paved path?