Yes, for most founders hope of future happiness varies linearly with the number of shares-- at least, in the region of the number of shares they have. If someone gave them 10% more stock, they'd feel 10% richer-on-paper. (There are anomalies at the extremes. E.g. if you got 100% of the stock, your cofounders wouldn't be motivated, and that would decrease the value of your shares.)