If the following correlations are true, then the opposite may be true (slave morality being better for improving the world through history):
Improving the world being strongly correlated with economic growth (this is probably less true when X-risk are significant)
Economic growth being strongly correlated with Entrepreneurship incentives (property rights, autonomy, fairness, meritocracy, low rents)
Master morality being strongly correlated with acquiring power and thus decreasing the power of others and decreasing their entrepreneurship incentives
If the following correlations are true, then the opposite may be true (slave morality being better for improving the world through history):
Improving the world being strongly correlated with economic growth (this is probably less true when X-risk are significant)
Economic growth being strongly correlated with Entrepreneurship incentives (property rights, autonomy, fairness, meritocracy, low rents)
Master morality being strongly correlated with acquiring power and thus decreasing the power of others and decreasing their entrepreneurship incentives