You have precisely no reason for believing that the growth pattern is exponential or an open-ended cycle. In fact the cardinal rule of economics ("things go on until they can't") suggests they will arrive in a steady state.
In order to figure out a likely steady state you'd have to look at the composition of spending and employment by people around or under the proposed income, and try to estimate shifts if there was an effective employer-of-last-resort in the form of a basic income. It gets complicated fast if you want to do a good job. Hand-waving about inflationary spirals is, on the other hand, easy.
In order to figure out a likely steady state you'd have to look at the composition of spending and employment by people around or under the proposed income, and try to estimate shifts if there was an effective employer-of-last-resort in the form of a basic income. It gets complicated fast if you want to do a good job. Hand-waving about inflationary spirals is, on the other hand, easy.