Did I cause this crash?

[Fonty]

Not guilty, if I was the Lexus driver and had two cars in front of me I wouldn't have put myself in the mix, I would've let them hammer it out first then go in afterwards with the trailing car, from my experience whenever another car comes into the mix like in this video someone is leaving the track.

 

[JulesDennis]

By doing what? He was as far left as he could go without hitting the barrier and was on the brakes from the moment he was alongside the braking marker cones. By the video, the Lexus braked over a second later, got alongside on the right and swerved across the track right to left, putting the BMW into the barrier.

The BMW couldn't have braked any more, and couldn't have been any more left. What was his chance to avoid this collision?

Check the video that OP has with the steering inputs.
OP breaks but does not downshifts at all.Just before the first contact he lifts his breaking ( break pressure there goes less that 50% in the bar).In fact his breaking is around that:50%-60% at average.Then contact is made and OP does lose speed because of wall,its the first time he goes from 6th gear to 5th.
If OP was going to downshift while breaking he could have a chance to avoid contact.Also he could actually break harder (he uses ABS if I am not mistaken and the car could break with 70-80% pressure without losing control).This does not justify Lexus.It does on the other hand shows that if OP wanted to break harder -trying to avoid that situation or Lexus dive in other words- he could have done that.He also had nothing to lose by doing that:Lexus goes by and off track (propably since most people think that he is going too fast) and he is still in first.
The other BMW is carefull,breaking already before OP/Lexus and has zero chance to pass there.
Like I said:they both wanted to get those turns in first place.OP had a good reason.He was in 1st place.
But he did not take into account what Lexus was doing and where that car was."I am first,I'll keep this (my) line,Lexus cannot pass me or try to do that here,he has to back off or run wide".(True from one point of view if actually you trust that Lexus is going to settle with 2nd place and not try to dive in order to go side by side with OP,then dive again to get his car in front).
Lexus wanted to get there first (corner where contat is made) and went into "I am gonna get my nose there first and make him back off".
BTW the outcome could have been different if that first contact was made a 0.02 later or earlier.Then it could be OP losing the car/going sideways or both of them.