Thanks for the extra context on Rhodes in South Africa, which is an accurate and valuable addition to the conversation. I'd still nominate him as an example of a rapacious colonist, based on the skirmishes, one-sided "treaties" and general land grabs that he made in the 1890s, stretching vastly farther north from Britain's initial presence in the South African Cape Colony. These fueled Britain's colonial era claims to what became known as Rhodesia (now Zimbabwe) and Northern Rhodesia (now Zambia).
Columbus ended up in 1496 as Spain's colonial administrator for what's now the Dominican Republic. He did that role badly, too, but what's more important is that he did it -- creating a colonial pathway that kept widening for centuries.
His wealth arose from snowballing into a monopoly the purchase of Kimberley diamond leases from other European settlers over 17 years with backers money and then his own.
For that matter Columbus was in truth a failed navigator and accidental colonizer.
His intent was sail to the already colonised spice islands of the Dutch East Indies ... but he'd made a boo boo wrt the circumference of the Earth.