What question?

Do you mean why are you doubting Doflamingo's abilities? To that yes you are doubting him. I never said Luffy will never beat him, I'm just saying he won't beat him on his first try (if they fight in this arc).
You don't know what I doubt because you can't read my mind. Don't say such silly things, and just to help you out I don't doubt his powers, I believe in, Luffy's power.
The question you should be asking is the none sense of people here saying that, Luffy can't beat him. You shouldn't be asking me this question. The fact that I didn't say I doubt, Doflamingo makes it quite obvious that you are picking at my judgment because you don't like it and that's why you asked a question that made no sense.
Let me enlighten you on something you can't seem to figure out.
Oda, has been slowly revealing, Doflamingo's powers. You have noticed right? Do I really have to bring you manga images to show you? Why has he been doing such a thing? He never did in the past, correct? The higher a persons common sense the closer they come to the correct answer. The lower a persons common sense the more many answers they get which can have answers that are all wrong or just one is correct. Here's the correct sensible answer. He's planning to reveal all his power when, Luffy and him fight because this is the arc in which he gets defeated by the future pirate king.
At the same time the only thing that can make, Luffy's fight with him a possible 1 loss is, Doflamingo's abilities being mysterious. Now, look at the paragraph I typed above. Understand now?
Now another thing you must feed your common sense is the fact that, Trafalgar Law ally to, Monkey D. Luffy is about to end up in a confrontation which will most likely result in an all out fight that will obviously not last long due to what I've said before, Law is near, Smokers level of strength and, Doflamingo laid him out instantly. He stands no chance but one benefit he can gain from this fight is figuring out how, Doflamingo's DF ability works. Due to the obvious fact that, Trafalgar Law won't be finished off due to an interruption from some bad ass heading towards, Green Bit he will escape with that information and possibly tell, Luffy.
Another thing you must remember is that, Luffy is a haki user and he has observation type. The force of, Doflamingo's strings wont always hit him since he will be able to sense how and where the attack will come from and because of that observation he will figure out that it's strings that are being used by, Doflamingo. He will be able to dodge them due to his observation. Any fighter with enough common sense which we may call a genius can figure out exactly what to do to fight against a DF ability such as, Doflamingo's. The part where I explained about how, Smoker can't even see, Luffy's top speed shows that, Luffy is on an entirely different level than, Smoker. All of you guys can only speculate. You can only guess with baseless information.
I have explained my many details and my reasoning as to why, Luffy would win this fight due to the fact that most of you do not have enough common sense and you keep pushing me to tell you more information. Details are a key and knowledge is power.
Again, do I have to continue telling you guys more details? All you need to do is use your common sense and look for details.
EDIT: So far from the information I have now my only guess as to what the fruit, Doflamingo ate is the Puppet Puppet Fruit. That's all I can think of now from what I've seen in details of the revealing of his abilities. I can come up with a better answer if we see more of his powers.
Doflamingo, may say. "I ate the Puppet Puppet Fruit, I'm a Puppet man."