Link: https://medium.com/basic-income/wouldnt-unconditional-basic-...
Basically, more and more money only chases the same amount of goods if the UBI does not exist as a transfer of existing money from top to bottom and middle as described in this piece, and instead exists as continual expansion of the monetary supply through newly created money.
Additionally, UBI does not eliminate forces of market competition. In fact, I argue it will even increase competition through increased entrepreneurship. It would be really stupid to raise your prices in a competitive market where your competitor does not raise prices, or even lowers them.
As a quick example, every year when Alaskans get their dividend checks, there are a lot of sales as businesses compete for that money. It would be a really stupid business in Alaska that increases its prices every time the dividend is distributed, in the knowledge people have more money to spend.
You may also find this argument interesting as well in regards to concerns of technological deflation: https://medium.com/emergent-culture/an-exciting-new-idea-in-...