is it profittable to open a server now?

Probably not.If you're just opening a basic factions server, you're paobably not going to succeed. You need something that sets you apart from everyone else.

Minecraft servers are always worth it, nice profit is always good XD

For profit? No. Games are hobby. If you need money get a job.

No. You need a lot of hard work, I think it's not worth it the relation job-money

I don't think so because the game is already dying and even the big servers struggle

Probably not.

If you don't have the motivation, or the creativity and skill set to create a unique server, you will probably not make it to any sort of big money.

It is not so easy to open a server, in fact, on the contrary, it is very difficult and you require a lot of free time to configure it.

Profitable, Not that much (unless you run some big as* network), as someone said the beginning is always hard, you will need to advertise your server well or you end up with no players

That's a gamble mate. You technically could but that also means you gotta work the advertisement and marketing in general, setting up a website and of course paying for aforementioned hosting.

Opening a server can be quite expensive, while you can use free/cheap plugins, hosts, builds, CMS, etc.
Not to mention, the EULA can cause a dip in profit considering that you are relying on pure kind-hearted donations or people buying cosmetics, this could be detrimental for some small servers. If you're starting out, use free plugins, and as you grow, start to use paid [or custom] plugins. If you have knowledge or skill in making plugins [or friends who do], why not give your server a unique identity and feel with a custom plugin?

tl;dr small servers, not much. especially including costs related with running and managing a server