How much was creating Google worth?

I would greatly ap­pre­ci­ate feed­back on whether the as­sump­tions in this post, as well as the con­cep­tual frame­work, are rea­son­able. I rec­og­nize that I don’t ad­dress pos­i­tive ex­ter­nal­ities ex­plic­itly. I think that they may be picked up im­plic­itly, but am un­sure about this.

Sergey Brin and Larry Page made an out­sized con­tri­bu­tion to so­ciety by speed­ing the de­vel­op­ment of high qual­ity on­line con­tent fil­ter­ing by cre­at­ing Google. They be­came spec­tac­u­larly wealthy as a re­sult, but plau­si­bly pro­duced far more value than they cap­tured.

One can es­ti­mate the value of cre­at­ing Google by try­ing to place one­self in the shoes of some­body with av­er­age US earn­ings in 2000 (~$45,000/​yr) and think­ing about how much one would be will­ing to pay for Google to have been cre­ated, rather than its coun­ter­fac­tual re­place­ment some years later.

As­sump­tion 1: The coun­ter­fac­tual re­place­ment would have been cre­ated 3 years later (in ex­pec­ta­tion).

As­sump­tion 2: Contin­gent on know­ing as­sump­tion 1, the mean 2000 US cit­i­zen would be will­ing to pay at least $1/​week (about 0.3% of his or her in­come).

The av­er­age per­son spends about 15% of his or her in­come on util­ities and en­ter­tain­ment com­bined. In view of this, we’ll assume

As­sump­tion 3: The mean Amer­i­can would not be will­ing to pay more 5% of his or her in­come for three years.

As­sump­tion 4: The per­centage of in­come that one would be will­ing to pay for Google is ap­prox­i­mately uniform over the en­tire pop­u­la­tion.

Put­ting these as­sump­tions to­gether, and us­ing the fact that world GDP in 2000 was about $60 trillion, we get a bal­l­park es­ti­mate of the value of Google of 0.6 trillion — 9 trillion.

Since Brin and Page have to­tal net worth about $40 billion, the re­marks above sug­gest that they pro­duced be­tween 15x and 225x as much value as their ag­gre­gate earn­ings.

Thoughts?