For practicing Jews: why have 5 calamities occured on Tish B'Av?

Tisha B'Av means "the ninth (day) of Av." It usually occurs during August.

Tisha B'Av primarily commemorates the destruction of the first and second Temples, both of which were destroyed on the ninth of Av (the first by the Babylonians in 586 B.C.E.; the second by the Romans in 70 C.E.).

Although this holiday is primarily meant to commemorate the destruction of the Temple, it is appropriate to consider on this day the many other tragedies of the Jewish people, many of which occurred on this day, most notably the expulsion of the Jews from Spain in 1492.

The three branches of Judaism do not have any differences about Tish B'Av. Yes, unfortunately another tragedy will occur. It will be another try at a holocaust or a full scale attack on Israel by the Middle East or who knows what. Man being man will always find an excuse to do the unthinkable.

because of sinat chinom (baseless hatred between Jews). Unfortunately which still exists.