This is why you should couple UBI with an eye-wateringly (90-95%) high tax on Land rents, (i.e, the value of the unimproved raw resource. "Land" is more than just plots of terrain: Mineral, Water, and Wildlife/Fishing rights - along with radio spectrum, etc all fall into this category.) Improvements and value-adds from human activity remain profitable, gatekeeping access to resources is not.
Economically speaking, your ability to compete for the extra disposable income is the same as anyone else's, but that money originated in the taxed rent from the Land you control, and any elasticity in demand for your Land caused by the increase in cash running around is priced in - if more people need what you have, your taxes increase along with it.
What remains for you to profit from is what service or value you add above and beyond the market value of the underlying Land.