Motivations
The monasteries, being landowners who never died and whose property was therefore never divided among inheritors (as happened to the land of neighboring secular land owners), tended to accumulate and keep considerable lands and properties - which aroused resentment and made them vulnerable to governments confiscating their properties at times of religious or political upheaval, whether to fund the state or to conduct land reform.
Monasteries are most likely to undergo such a fate when coming under a Protestant or secularist regime. However, Catholic monarchs and governments are also known to have taken such steps at some times and places. Similar confiscations also happened in Buddhist countries.
There are also known cases of specific monastic orders being suppressed by the Catholic Church itself, such as the suppression of the Jesuati by Pope Clement IX in 1668 or the (temporary) suppression of the Jesuits in 1759 (though the Order was eventually restored, many of the properties confiscated from the Jesuits were not given back). Additionally, there were cases of specific monasteries at various times and places being disbanded as a result of power struggles within the Catholic Church. For example, the Cârța Monastery in Transylvania was disbanded in 1494 by the apostolic legate Ursus of Ursinis.