Flight makes a CR 4's life difficult.
Flight is actually less of a problem at lower levels than it is at higher levels. This is because the difference between non specialized ranged attacks and specialized ranged special attacks is a lot smaller, so the melee characters are losing less of their ability to fight back.
At higher levels flight magic is more readily available but dragons still fly faster and the ranged attacks of non specialists are hopeless.
Unfortunately SorO is more interested in measuring his penis than having a discussion which is why he continually misses the point entirely.
The CR 4 10 HD dragon is an example of a single enemy that is under CRed in a manner that is very obvious to any observer. The Adamantine Clockwork Horror is also a single enemy that is clearly under CRed. SorO's argument is that because that single age category of a single dragon exists, all dragons are under CRed. By the same logic so are all constructs. They clearly aren't though as one enemy having odd stats does not mean everything that shares the same creature type also does!
I've stated that things with low defensive stats would die quickly. I consider that to be obvious.
I haven't insulted anyone, and I haven't fed into your attempts to bait me into a dick measuring contest. As for the wealth, that misunderstanding has already been straightened out and you are still wrong as level 4 NPC wealth or even level 4 PC wealth cannot afford the things you say it can. As long as we're on the subject of pointing out mistakes though how about assuming a buff applies to 3-5 weapons when it applies to two, or taking a feat that it cannot possibly take and can barely make use of?
I accept you are unwilling to have a productive discussion, but there are others here that are so here is the breakdown of the different dragon types:
Wyrmling dragon does about nothing to the party. Even its best trick consumes a few wand charges and imposes absolutely no real danger. There are plenty of encounters that would impose greater risk, and this one is not a threat at all.
The 7 HD dragon fares a bit better but still lacks the resources to be dangerous, so aside from taking longer to die this plays out the same as the CR 2 dragon.
The 10 HD dragon despite this specific enemy clearly being under CRed due to having the exact same CR as the previous dragon who has lower stats is capable of presenting a threat, but still is not that big of a deal. Either it attempts the same breath technique that it is only slightly better at than the wyrmling and dies within 4-7 rounds so that it cannot do that twice... Or it goes for a melee approach which works a bit better until the party starts keeping ten feet out of its reach, shutting down its full attacks while still able to use their own single attacks or in the case of the strong Barbarian using Pounce can still use a Chronocharm or Sudden Leap or some other such ability to move back after unleashing a charge. The dragon is a bit too low to be able to get access to Pounce itself and because this is lower levels most of the party isn't dependent on full attacks yet so the dragon is at a considerable disadvantage if it goes this route.
And those are the only two things the dragon can do. Its Cha is too low for offensive spells to work, and most of the good offensive spells at this level work better when there is someone there other than you to follow up. The dragon is alone, so it doesn't especially benefit.