The question falls is related to a large area of research showing that people are egocentrically biased when they think about the thoughts and feelings of others.
The classic study is Ross, Green and House's (1977) paper on the false consensus effect, according to which people overestimate the extent to which their own beliefs, opinions, behavioral choices and traits are shared by others. For example, when they asked participants whether they would allow a supermarket to use their endorsement of the store in an ad, 66% said that they would agree and they believed that 75% of the people would do the same. The 34% who said they would decline the request believed that 43% of the people would do the same.
This effect is highly robust and similar phenomena have been studied in various domains, sometimes using different terms, such as social projection, egocentric bias, hot-cold empathy gap, "curse of knowledge"-effect, or hindsight bias.
A good primer to the literature is the chapter Van Boven and Loewenstein (2005) which lays out several ways in which people can be inaccurate in thinking about the minds of others.
Ross, L., Greene, D., & House, P. (1977). The “false consensus effect”: An egocentric bias in social perception and attribution processes. Journal of Experimental Social Psychology, 13(3), 279–301. http://doi.org/10.1016/0022-1031(77)90049-X
Van Boven, L., & Loewenstein, G. (2005). Cross-situational projection. In M. . Alicke, D. A. Dunning, & J. I. Krueger (Eds.), The Self in Social Judgment (pp. 43– 64). New York, NY: Taylor & Francis.