If you have big website with lots of images and videos and you do not want your customer having any problem while surfing your website than you need dedicated server. If you have small website than you do not need dedicated server.
i have allways ran with vps and i have had no problems with this i think im in love with vps , i have had friends who have had dedicated servers and they allways seem to have to do alot more work than i do on my vps and they also pay more up to you what you want or need to my option would be a nice vps or a hosting from a company ran on vps
If you just beginning your journey with big website and massive of traffic better get VPS package first, move slowly to dedicated one accordingly. VPS is the best choice at the first place
If it's a small business I say stay with a VPS until it gets to a point where you require more resources as traffic increases. When this stage occurs, just buy a dedicated server.
If you're just starting out, a VPS is great, and you can always upgrade to a bigger VPS plan without having to move your files to a new server. Once you've got a lot of heavy users, then a dedicated server is your best bet.