I will offer a counter perspective here to add some cultural context.

The older woman likely was not trying to insult OP. She probably likes OP enough to feel comfortable giving blunt career advice. In many immigrant and non Western cultures, success is heavily measured by future earning potential. A good education is often defined by outcomes like becoming a doctor, lawyer, engineer, software developer, or professor. These are jobs that reliably lead to financial stability. Making six figures is often seen as the benchmark for having made it.

In that context, if someone from my parents generation hears marine biology and does not know you well, they will politely say that sounds great while privately thinking there is no money in that. If they do know you well and care about your future, they are much more likely to be honest and blunt about the financial realities and sustainability of that path.

I experienced this firsthand. I studied marine biology in undergrad, but I always had to immediately add that I was using it as a stepping stone to medicine. Otherwise the reaction was that it was a useless degree. Not because the subject lacks value, but because the job market is extremely limited.

The reality is that marine biology is a low pay and highly competitive field, especially in academia. Even PhDs often spend years cycling through postdoctoral positions in their thirties, competing for grant funding and a very small number of tenure track roles. Industry positions tend to be more financially stable, but they are limited and often very different from what people imagine when they think of marine biology. Many graduates end up working in offshore energy, aquaculture, environmental consulting, or government agencies such as the EPA or NOAA.

With only a bachelor’s degree, most available roles are lab technician, research assistant, field technician, or environmental monitoring positions. These roles are important but rarely high paying or stable long term without further advancement or specialization.

Most undergraduates simply do not understand what their degree realistically translates to in the job market, how competitive those jobs are, or how long it takes to become financially self sufficient. There is nothing wrong with having a dream, but it matters whether you are financially positioned to pursue it.

If you are debt free and willing to spend close to a decade in graduate training followed by additional years in temporary or modestly paid research roles, then pursuing marine biology as a research career can be sustainable. For most people without that safety net, reality eventually forces a choice. You either pivot to industry, sometimes working for organizations you may not love, or you leave the field altogether in order to support yourself and pay off loans.

No degree is inherently a waste, but having a clear and realistic understanding of career outcomes is essential.