library(MASS)

beta_1 <- data.frame(ls=rep(0,1000), bisq=rep(0,1000))
for (i in 1:nrow(beta_1)) {
   x <- rnorm(100)
   y <- x + rt(100,3)
   beta_1$ls[i] <- lm(y~x)$coefficients["x"]
   beta_1$bisq[i] <- rlm(y~x, psi=psi.bisquare)$coefficients["x"]
}

apply(beta_1, 2, sd)

> apply(beta_1, 2, sd)
       ls      bisq
0.1809239 0.1296139

beta_1 <- data.frame(ls=rep(0,1000), bisq=rep(0,1000))
for (i in 1:nrow(beta_1)) {
   x <- rnorm(100)
   y <- x + rnorm(100)
   z <- rbinom(100,1,0.05)
   y <- y + z*rnorm(100,0,5)
   beta_1$ls[i] <- lm(y~x)$coefficients["x"]
   beta_1$bisq[i] <- rlm(y~x, psi=psi.bisquare)$coefficients["x"]
}

> apply(beta_1, 2, sd)
       ls      bisq
0.1518029 0.1147156