Why does HF generate a carbocation with an alkene
However I felt like the bond strength of $\ce{HF}$ is so high that it couldn't be possible to cleave it for the donation of $\ce{H+}$

HF has the highest single bond energy and hence you were right in expecting that it may not dissociate.However in concentrated solutions, due to the formation of stable hydrogen bonded complex $\ce{[HF_2]-}$, the reaction is pushed in the forward direction making it  a resonably strong acid (in fact strongest among corresponding concentrated solutions of all the hydrogen halides).So, you could generate a carbocation with that.However, as generally dilute solutions are used which are economically feasible, more stronger mineral acids in dilute solutions  like $\ce{HCl, HBr}$ and $\ce{HI}$ are used.
EDIT:
As suggested by Oscar Lanzi in the comments, acids like $\ce{HCl, HBr}$ and $\ce{HI}$ are safer to handle when compared to $\ce{HF}$ as the reactions of $\ce{HF}$ are associated with highly negative enthalpy changes [highly exothermic]