there's not a lot of risk for white, and it's really easy to remember the moves
Changing opening around 1500

I don't care what your "real rating" or whatever is. Either way, asking someone to play Ruy by messing around with it without understanding it first is dangerous advice. If you're higher rated like you implied (I doubt it), you should have known better.
It's not dangerous advice. It's so silly when some people say this. "Don't play the Sicilian. That's DANGEROUS. Don't play the Ruy Lopez. That's DANGEROUS. You don't know what you're dealing with!"
Like what? You could lose a game? That's all a normal part of learning. You play to learn and understand better.
Playing this kind of chess "with the bumper pads on" isn't 'safe' or helpful. People need to be exposed to new ideas and concepts in order to get better.

Best thing I did last years was downloading a free database program in which I store my studies (not only opening, also middle game and endgame) and store and analyse my games. Changing openings would feel like a waist to me. I would have to start again.

i mean don't listen to any of my opinion, i'm very lowly rated, but Vienna Game and the Queen's Gambit are both really good

Yeah u are right.Its so silly that even people of strength who are significantly higher than u and me and have been coaching for decades recommend to spend more time on tactics and other parts of ur games instead of learning gallons of theory (i am not saying that learning theory isnt important).No one is stopping him from Playing it but do u know playing an opening and building a repertoire is completely different?I am not saying that everything u said is false but it's not a 100% correct as well.
I never said anything about learning loads of theory. If you are comparing it with memorising long lines of theory, that's not what I meant at all. The level of learning the opening I would recommend is learning as far as certain tabiya positions around move 10 and then, like you said, also learn about tactics and endgames.
There are a lot of coaches who will tell you that openings are important. Learning about tactics, positional concepts and structures defined by the opening helps you understand the game.
You can't even separate tactics and middlegame play from the opening as the opening defines the structure in which this occurs. The endgame comes from the middlegame. The middlegame comes from the opening.
Even during the endgame you can often recognise that a particular scenario and structure has come from a particular opening.

everyone forgets we are different people with different religions with different countries with different cultures. if we were so critic about each other, how come every grandmaster has a different opening?

we all get by with different skill sets, and different preferences. you don't see the grandmasters criticizing each other for their openings...

also if someone feels so strongly about an opinion, why even bother to get him out of the habit? them being bad is not affecting you in any way...? correct me if i'm wrong

i mean don't listen to any of my opinion, i'm very lowly rated, but Vienna Game and the Queen's Gambit are both really good
Feel free to say whatever you think. Those openings are both very good.
I would prefer the Queen's Gambit.
Vienna Game is kind of allowing black to equalise. Nf3 is more active and aggressive as it pressures black's centre. It has some tricks though.

also if someone feels so strongly about an opinion, why even bother to get him out of the habit? them being bad is not affecting you in any way...? correct me if i'm wrong
Because it's fun to talk about chess and different openings. I might disagree with him but I am enjoying expressing what I think and the kind of play that I enjoy whereas the other person can do the same.

very good point. i just thought you were being heated and arguing about it
I don't see it that way as we are both making points about chess and discussing chess.
It's totally different if someone starts being rude to me and making personal remarks.
I don't care what your "real rating" or whatever is. Either way, asking someone to play Ruy by messing around with it without understanding it first is dangerous advice. If you're higher rated like you implied (I doubt it), you should have known better.
It's not dangerous advice. It's so silly when some people say this. "Don't play the Sicilian. That's DANGEROUS. Don't play the Ruy Lopez. That's DANGEROUS. You don't know what you're dealing with!"
Like what? You could lose a game? That's all a normal part of learning. You play to learn and understand better.
Playing this kind of chess "with the bumper pads on" isn't 'safe' or helpful. People need to be exposed to new ideas and concepts in order to get better.
I think they say that to beginners so they can have a good experience and not go too deep in opening theory, in the sicilian case that is a thing since only 1 move changes the entire ideas of the game and the position, but the ruy lopez i really didnt get it, i saw some videos and it looks like a pretty solid choice for beginners(if you cut out the fact theres is like 8 variations in the closed ruy)
it's a really solid opening