No Stupid Questions

Dogs don't work like that. A dog gets protective when it's anxious, and thinks it has to be in charge because you are ineffective. If your dog is relaxed and looks to you to protect it, you are doing a good job of raising your dog.

Dog park, I dunno, but "standing up to other dogs' just sounds like asking for a dog fight. Playing dogs are not necessarily jockeying for dominance but even if they are it doesn't mean they can't all have fun, without being mean.

I agree that even good, happy dogs can have a nose for danger, our awesome shep-akita was pleasant with adults and gentle giant with other dogs but once was so growly snappy with a girl my stepdaughter brought home and she did steal something. The dog picked up on her we did not.

Wow your comments are scary.

You are definitely not fit to have a dog right now.

Go read about dogs care, extensively, and in the meanwhile do not try to do anything to this poor dog.

"I saw my kid be nice to people, but I want him to have the instinct to instead beat them up with a baseball bat, how do I do that?"

And the little mention of "but I'd like to not abuse him too much if possible" at the end. That's really disgusting.

You wanna change a nice dog because is not useful to your needs? You don't deserve a dog.

Dogs generally have a good sense if something is wrong or if someone is being aggressive towards you.
You don't have to (and shouldn't!) make a dog "mean", he's perfectly capable of it if he feels something is up.

I used to have a dog, her name was Zöe, named for one of the characters on Firefly.

She was the best dog. Completely safe around children and the elderly, never barked, never nipped or bit, she was smart, observant, and just the biggest sweetheart.

But if she determined that you were disliked by Her People, you weren't safe.

My wife told me a story about Zöe, that happened while I was at work. We used to live by a river - it was literally in our back yard. A couple of guys showed up, ostensibly to ask if they could go fishing but more likely to look for things they could steal, as the river was maybe 6" deep at that time, and there were much more accessible places to get to the river. My wife wasn't comfortable with them there, but they weren't taking No for an answer. Our other dog was bouncing and barking from the back yard, and they were worried about her, and as a result, they didn't see Zöe, until she started this angry hateful growl that was accompanied by bared teeth an inch long and a 4" wide strip of fur standing up along her back.

This dog could run nearly as fast as a whitetail deer. She once ate half a snapping turtle. She was part hound, part alligator, and part backhoe, with a little bit of two-stroke dirt bike tossed in. She was unbelievably fast and strong.

My wife said "I can't really control that dog, you really need to leave." And we never saw them again.

Tl;dr: Your dog is very likely only nice to YOU and people you are comfortable with.

Edited to add more info about Zöe because she was such a cool dog and I miss her.

I agree with the commenter who said dogs usually have a sense for danger. If someone is breaking into your home, your dog will be the first to know, and then let the household know. There's some statistic I can't recall exactly, but people are less likely to continue breaking into a home if a dog is barking (like a German Shepherd barking, not a Chihuahua

The temperament of your dog also largely depends on its breed. Some dogs are friendlier than others, or some are perhaps more suited for protection than others. If you want a family guardian, you'll probably have to invest (money and time) in the breed + training for said dog.

Your pup being "too nice" isn't a problem, it sounds like you have a happy, friendly dog for your family.

Why not just enjoy your dogs personality and treat him with love and kindness? Dogs are the most loyal domesticated animals on earth that deserve all the respect and love we can muster to give them. All dogs will guard their owners if they respect you and think you are a part of the pack. And just for the record I believe the Pitbull breed needs to be retired for good. There are too many instances of them harming and killing other dogs and people including their owners and small children.

My advice is not to try to make him mean.

If you want him to protect your home you can train him to bark at strangers when at home.

Why not hire a service that will train your dog to be a guard dog. You want a guard dog to do a lot more alerting than attacking.

You don't want it mean, you want it effective.

Leave it alone with a husky for a while. The husky will teach it how to assert itself without being mean.

Breed?