I need help with this whole Media Server

So, I'm trying to figure out what’s the best path to take, what I need, and how to go about it and if I'm on the right path. I’m trying to start my own Media Server for my family so that I can have my own place for movies and shows so that I can stop paying for subscriptions. I'm not good at the whole tech stuff, I don't know my own butt from a hole in the ground in this area. I also have been saving up for this whole process, about 5,000 USD just for this, I was hoping to give this to my family as an early holiday gift. I was doing a little research for storage and came across UGREEN NAS DXP4800 Pro 4-Bay, is this a good storage option for someone like me that doesn’t know much about the tech empire and exactly how much storage will end up needing. I've also read somewhere that I need something that can stay running all the time to run the media server. Would my old potato HP work for that or should I fork out loan for an old work pc. I plan to have 4 8Tb hard drives for it so that everyone has enough room to have all the shows and movies they want, like supernatural, bob's burgers, twilight, lord of the rings, some anime (I’m hopping all of one piece but I know that I'm asking far too much with that one, lol), also I would like for everyone to have their own personal files for photos and what not. For a Media server, I have a mother breathing down my neck about how she doesn't trust plex, jellyfin, etc. I understand her reasoning behind Plex, the lifetime subscription is about 750 USD and what happens if they goes bankrupt. I know there’s an offline mode, but I don't really know much about it and how reliable it is. For Jellyfin she’s worried that it can get hacked and our information can get stolen or something like that, which I replied with we would need a VPN so to make sure its secure (I’m not a 100% and I’m still unsure about). All in all, she’s just scared that we can have our information stolen or something worse could happen (she practically lives in the hypotheticals), I don’t blame her, this is new to me too, I don’t know the risk of having something like this. I also don't want to give an answer that I have no clue about. Is there another one, I've mostly seen stuff about Jellyfin and plex. So far, my shopping cart consists of (I plan to wait until black Friday or cyber Monday to make any final decisions) 4x Seagate 8TB IronWolf Internal NAS Hard Drive ($1,319.96) UGREEN NAS DXP4800 Pro 4-Bay ($699.99) *Verbatim Ultra HD 4K Blu-ray Writer, USB-C, BDXL and M-DISC Support ($275ish) which rounds out to be just over 2400 usd Before I go spending all this money, I would like to know if I'm on the right track, is there anything else I need to know, should I go a different way, and what else do I need to know before continuing, any risk or hazards to look out for? Thank you in advanced. And if you made it this far here is another thanks for reading all of that and I’m sorry for the book. edit. the main reason for going so expensive is because we would like in the future to have camera footage linked to the storage. plus my uncle is disabled, he cant walk so he spends most of his time watching movies, shows, and other things. he also has times when has really bad ER visits that last a while sometimes even 2 weeks, I would like to have it were he can just watch what he want to when he wants and not relay on tvs in the ER.