The phrase "long horizon" means looking at or planning for events far into the future. It suggests having a broad perspective and considering the long-term consequences instead of focusing solely on the present moment. Full definition
What initial retirement portfolio withdrawal rate is sustainable over long horizons when, as currently, bond yields are well below and stock market valuations well above historical averages? (cxoadvisory.com)
But they are still relatively exotic, and appropriate only for investors with longer horizons and an understanding of the risks. (aaii.com)