Why do you think the speaker of the house is next in line to become president in the event of the death of both the president and vice president

The Speaker of the House is next in line because the House of Representatives was traditionally seen as the "people's house" or the most Democratic house. It wasn't until the early 20th Century that the Senate was elected by the people directly, so the leader of the more Democratic house was a fairer pick in the line of succession.

i think its the outcome of people's preferences.