The problem that I am seeing here is that the opinion of your peers could potentially be uninformed (due to still being in high school and therefore not having attended university and/or worked in the field), which I believe would not give you the best insight into the Bachelor of Commerce. I would therefore suggest speaking to people that are in the field, whether it be university students or employees as they are likely to provide more accurate thoughts on this matter. In addition to this, keep in mind that a Bachelor of Commerce is a multifaceted degree and is not strictly limited to finance. This means that there are other fields that you could specialise in, either instead or alongside finance. In the case of USyd, examples include:
- Marketing
- Industrial Relations and Human Resource Management
- International Business
- Accounting
- Business Analytics
In the case of a Bachelor of Commerce, supply of labour and the number of available employment opportunities depend on the major in question. Not all majors are the same, and finance could be less/more difficult to be employed in than other fields.
The same suggestion (although probably a more accurate one in this context) can be said about the legal industry, where competition is high among graduates, and where receiving a job offer typically requires meeting challenging criteria (including favourable university performance and gaining some form of work experience, such as through a clerkship).
Data science and project management both seem like interesting fields. If you believe you would be interested in studying a degree in either field (or any other field for that matter), there is nothing stopping you from doing so. In order to make an informed decision, you should also seek insight into both a degree with a focus on data science and the Bachelor of Project Management prior to making your decision.
I hope this helps!