Sure I’m not the first person to come up with this, but here we go:
Couple of facts we know: Charles Widmore acquired a fairly large fortune while spending time off the island. Charles Widmore, was not the leader of the Hostiles for a time, but became the leader after Eloise left the island, presumably soon after she shoots her son in 1977.
My theory: Widmore and Hawking were not the leaders of the Others during 1954. They were most likely in training to be named the leader. At some point during the late 1950’s Eloise was named the leader by Jacob, and Charles was upset by the choice that was made. When the Dharma Imitative scouts came to the island in the late 60’s/ early 70’s to determine how to set up the commune, they ran into the Others. Charles still being upset by Eloise’s appointment, worked out a deal with the leaders of the D.I. to set up a truce with his people. In the deal, not known to the Other’s, Charles was given large amounts of money and holdings by Alvar Hanso, and the D.I.. He then began taking many trips off of the island, setting up his corporation and life off of the island. His plans were disrupted when Eloise suddenly gave up her position, and he became leader of the Others. He then stayed on the island leading the group, until his life off the island was discovered by Ben, and he was exiled.