No doubt there are both conspiracy theories and conspiracy facts. But how many conspiracy facts were first conspiracy theories? What is often a trait of something that is labeled a conspiracy theory is a lack of evidence (hence the typical pejorative usage). Conspiracy facts don't have that problem. A few conspiracy theories no doubt turn out to be conspiracy facts. But I think it is a minority. Reading a list of conspiracy theories is like reading the National Enquirer. Three fourths or more is complete BS but at least one of those stories is true. Also, see the movie "Conspiracy Theory" with Mel Gibson...
As far as the world trade center, I fall into the "fire weakened the beems" category because that is factual. Much of how and why WTC 1 and 2 collapsed the way they did can be explained by their rather unique support structure. Also they did NOT fall at free-fall speeds (it was ultimately about 2/3 free fall speed). See https://www.tms.org/pubs/journals/jom/0112/eagar/eagar-0112.html for the best explanation I have seen.
It points out that the fire would not have burned nearly hot enough to melt steal and even concluded that the amount of weakening would have been insufficient by itself to cause collapse. However:
"The additional problem was distortion of the steel in the fire. The temperature of the fire was not uniform everywhere, and the temperature on the outside of the box columns was clearly lower than on the side facing the fire. The temperature along the 18 m long joists was certainly not uniform. Given the thermal expansion of steel, a 150°C temperature difference from one location to another will produce yield-level residual stresses. This produced distortions in the slender structural steel, which resulted in buckling failures. Thus, the failure of the steel was due to two factors: loss of strength due to the temperature of the fire, and loss of structural integrity due to distortion of the steel from the non-uniform temperatures in the fire."
There's much more and it is a far better explanation than "it looked like a controlled demolition so it must have been". Intuition can be useful but it is no replacement for hard facts.