Rich authors

Not likely.
Ripped right out of The Publishers Lunch mailing list I subscribe to. This is from their weekly lunch, latest issue.

(START QUOTE)
The Key
As usual, the handy key to our Lunch deal categories. While all reports are always welcome, those that include a category will generally receive a higher listing when it comes time to put them all together.
"nice deal" $1 - $49,000
"very nice deal" $50,000 - $99,000
"good deal" $100,000 - $250,000
"significant deal" $251,000 - $499,000
"major deal" $500,000 and up
(END QUOTE)

And that's the gross pay. Even in an American market taxes have to be deducted. As that market also differs from the Swedish one you'll most probably be represented by an agent who wants their 15% share of the amounts above.
In reality a debut in the genre I'm interested in pays about $5000 in advance, and considering that 99% never get as far as a debut and you're not especially welcome with more than one book a year we're in reality talking a month's pay for a year's work.
They say writing is a work of love. It had better be a lot of love. Still want to walk that path?