None of this changes the fact the we have a limited number of supplies on this planet (and we've somehow let corporations start buying exclusive rights to fresh water supplies), but if you think you are properly equipped to build a floating ocean fortress or a cave-lair deep under someone else's property, feel free to try.
Why are you assuming that people can not group together and pool their wealth and resources? Almost no one starts a business with just their own savings any more.
What if someone already bought up all the resources and sells them to those pools of people at super-outrageous prices that prevent them from properly starting a business? Total control of an asset prevents competition, and just assuming "someone will invent something better!" does not work for all cases.
Life isn't an Ayn Rand novel