There are risks, but there also risks from putting off settling down or losing yourself to marriage at any age. There are always going to be pros and cons, so not unreasonable to have a few concerns and 'what ifs', but there aren't any of the red flags that jump out to me when it comes to early marriage. I think, as others said, supporting wider relationships and activities is a great way to help reduce some of the risks of getting stuck and missing out.
I married at 18. My brother married at slightly older. For both us, we had chaotic, very unnormal teen years and married someone we had known and had been dating from about 16, though I had dated multiple people up to about 6 months before I got married.
For him it was a terrible choice because it locked him into the youth party lifestyle when he wanted to move out of it with someone who was terrible (like the gives spiked drinks to underage kids for her own amusement terrible) even if she accepted him after his expulsion/arrest when made others had turned their back on him. He needed to work through that his teenage foolishness wasn't going to make everyone see him only by those mistakes, serious as they were.
For me, it's still one of the best choices I made and I've done so many things I wouldn't have had the chance to do otherwise. We'd discussed our future so much and went into marriage having worked out most of the bumps in our communication needs to work towards things together. It comes down I think in part to choosing a partner well and the mindset of going into marriage expecting it to be the start/part of growing with each other rather than expecting it to be static from there.
Everyone misses out on some things, no one gets to do everything and they all have their benefits, risks, and responsibilities. Some miss out by jumping into something too soon whether it's marriage, a career, children, and others by putting things that matter to them off and still others by having forced outside of their control change everything or getting too absorbed into one area of life to the exclusion of others.
I think I would have missed out more if I'd said no to marriage. I certainly wouldn't be where I am now.
I can't see what ten extra years of being comfortable in a relationship can bring you in terms of personal growth. Few people think 'oh I wish I'd never done all that travelling and clubbing I wish I'd had more time infront of Netflix and worrying about what we do if the boiler breaks!'
I had the living on my own, doing whatever whenever, Greyhounding around the US at a moment's notice and kipping on strangers couches and beds for most of my teenage years due to my parents being as they are. I wouldn't say I regret it, but I think I'd be just as happy and as I am without it. None of them were that great and I most certainly would not say I got any 'personal growth' from going to DC Pride on a day's notice (I found it less fun than the ones I was involved in organizing at home) or from spending a long weekend in New Orleans or spending a week doing the under-21 clubbing scene in Myrtle Beach even getting to experience a double tornado event (watching people film tornados on hotel roofs was interesting though not a growth experience) or any of the other travel and clubbing bits I did. They had their fun, but I grew a lot more at the same ages from caring for my dying grandmother and our wider family through her last days, taking up new sports and classes that were well outside my comfort zone, and actually from being online and cultivate online relationships that gave me the chance to leave. Those made me more who I am than the Florida spring break that I probably should not have done - that one I do have some regrets about.
I grew more post-marriage (but then Netflix didn't exist when I got married and I don't use it much now). My marriage gave me new stability, options, and really just the feeling that I could do anything with that support. It's not always been comfortable, immigrating was difficult, having children is challenging, and I did have a wobble around my early thirities, in part from having fallen in with people who perpetuated the idea that marriage, especially to a man, was the main source of women's misery. Maybe that's true for some or at a population level, but at the time my misery was coming from undealt with childhood/teen issues, dealing with multiple family members facing terminal illnesses, my own health changing my plans, and unsupportive systems making everything more stressful. My marriage was an easy target as it was one of the very few things in my life at the time I had some control in.
My marriage helped me get through that once I saw that, my spouse helped me see wider possibilities and to accept that losing what I thought was my dream career, and for a time the ability to walk unaided out of the house or even get out of bed, and all these people I still miss dreadfully didn't mean I'd lost the ability to accomplish anything worthwhile or interesting. Life can throw many things out way, at any age, and whether or not marriage makes us miss out involves more than just the being married part.