Tons of things are done in good faith that don’t work out for many reasons. The top universities really don’t care if a few ED’s decide not to come, they literally have thousands of applicants who are just as well qualified to take that slot. ED is fairly effective in preventing anyone trying to “game” the system. GC will only allow one ED/SCEA/REA application to go forward and you must commit to your ED acceptance before any RD acceptances come out. IOW you can’t get an ED acceptance and then wait for any other acceptances and then choose.