This isn't a perfect example of price, since it's simply from Amazon, which varies by supplier, but it's a reasonable standard.
A Nintendo 3DS XL costs: £150.00 ($246.35)
A Sony PS4 costs: £349.99 ($574.79)
The PS4 is over twice the price of the 3DSXL.
That is a very very steep price for a single Christmas present. Now I know my situation will be different to lots of other peoples, on the basis of how much money my parents earn in a year and how many siblings I have (I have 2), but each year my Parents tend to spend approx. £300 on each of my brothers and me.
If I wanted a PS4 it would be the entire worth of my Christmas presents, and a little bit more.
My parents could not feasibly afford to give me any other Christmas presents at all this year.
Meanwhile my brothers would get £300 worth of presents bought for them, which would come in the form of a number of items.
I would be stuck with one thing (this price doesn't even come with a game, by the way) and my brothers would have lots of others. While I would pretend not to be, there's no way I wouldn't be atleast a little bit jealous of what my brothers have.
And my parents would know this, and they would feel very bad if they gave me one thing for Christmas, even if it was very expensive, if my brothers had lots of things to use and play and enjoy.
If you have siblings and you have parents who aren't on mega-wages, then buying an expensive games console for one child is very unfair and difficult, both on the child who recieves it and on the children who don't.
The PS4 might be capable of playing multiplayer games, but a lot of games you will want to play will be singleplayer games, meaning you won't be able to play with your brother, and it can cause fights and arguments.
And also bear in mind the cost of actually getting you games for the PS4. Purchasing the console with a game costs even more than the price above, and new games at the moment will be upwards of £60 ($98.50) for each new game.
Also bear in mind the fact that your brother is getting a 3DS XL, which isn't as expensive. He probably won't have as many things as you at Christmas, but he'll have a few things. More than you would have extra if you got a PS4.
If your brother already has a 3DS it's also good for sharing, because the two of you can play both of them together. That's the sort of things that parents approve of in toys and consoles.
Maybe your parents will be able to look into getting a PS4 for you and your brother to share in the new year, when the prices start to dip a little bit and it becomes more affordable.
Try to remember that your parents are only trying to do the best they can. Christmas is really difficult for parents. And if you have multiple children it's all the harder to stretch your money and make sure that all of them get equal amounts of things.
Try to not be too upset about it. Your parents really just want you to have a good Christmas. They can't fulfill everything you desire, but I'm sure they're trying their best.
Keep a smiling face on and be happy with what ever you get for Christmas. It really does make your parents happy to see that you're happy. And at this time of year, parents put a really large amount of effort into making sure that you're happy.