Question: “Is it better to start off as a software engineer or as a product manager if you want to pursue your own startup in the future?”
You won’t be able to start off as a product manager (in a true sense of PdM responsibilities and experience, not in a title) since this role requires having a lot of experience from various disciplines. Product management (again, true responsibilities, not a title) is a multi-disciplinary field that requires a healthy mix of product building experience, technical knowledge, user experience understanding, design knowledge, and marketing expertise. These are not the things that people come to the table with right out of college or grad school – in fact, not many get to build these over time. In fact, I worked with many “product managers” who were stuck in one of the areas they felt comfortable with and not dared to venture into others. This would almost always make them very good in that particular area (say – technology), but rarely makes them good product managers.
With that said, if you are targeting your own startup in the future I think you better off coming from a different angle. Start off as a sales engineer or sales rep.
Because ultimately, no matter what you do in your startup, the only real metric of your success would be the sales figures. Even if the only thing you would have sold is your startup to another company – sales is probably the most important part of product life cycle.
As a sales rep/engineer you get an unfettered access to clients, their pains, wants and needs. You get first-hand accounts of pains and issues your clients want to solve using your product. This way you can be sure your product isn’t a “solution looking for a problem to solve”, but a true pain relief.
It’s very easy to justify NOT talking to your clients as a product manager because you’re too busy or whatnot. I’ve heard this pretty much from every single product owner and product manager (and I am myself was briefly guilty of this) – “I am too important and too busy to talk to customers”. Everyone has to grow up and out of this mindset. If you come to your startup already out of this mindset – you will have a greater chance of success. As a sales engineer or sales rep you don’t have a way to get out of talking to your customers – it’s your job.
As an insight – almost everyone with responsibilities of Director or VP of Product has sales metrics as part of their core KPIs. As a startup founder (or one of them) and a person who envisions and creates the product (assuming you’re eyeing a product startup) you would be responsible for product’s success. Unless you’re giving it away (and even in that case) – your main measure of success would be the number of customers. Being able to sell your product is a huge part of Product Manager (and above) responsibilities. If you are planning to start up your own venture, the ability to sell is probably just as essential as the ability to read, write and create PowerPoint slides.
TL;DR: start as a sales engineer.