Singularity of Furstenberg measure for infinite covolume discrete subroups in higher rank

We consider symmetric random walks on discrete, Zariski-dense subgroups $\mathrm{\Gamma }$ of a semisimple Lie group $G$ with Property (T). We prove that if $\mathrm{\Gamma }$ has infinite covolume, then the associated hitting measure on the Furstenberg boundary of $G$ is singular. This is in contrast to Furstenberg’s discretization of Brownian motion to lattices, and it is the first result of this type when $G$ has higher rank.