I do think the spike protein increases risk of blood clots in some people -- this is true if they get via vaccination or if they get it via an infection. The amount of spike protein you get is thousands of times less with the vaccine than with a natural infection, but if you are sensitive to it in that way, it could certainly pose a problem. This is separate from the issue with J and J vaccine with low platelets and brain clots.
We know that the rate of thromboembolism in COVID infected patients that require hospitalization is about 1 in 5:
DEFINE_ME This is actually a really high number and hopefully puts things in perspective. I have friends who work in the ICU and they tell me that in spite of standard anticoagulation therapy, there are COVID patients that get massive blood clots. I had a friend who was in his upper 40s, diagnosed with COVID -- moderate infection -- sent home on some steroids and inhalers and then dropped over and died of a pulmonary embolism while he was mowing his lawn.