no, there's a table to determine it based on your Bracket and Division and amount of SPS
This table will show you the max amount you can get:
And this old table will show you how much SPS you need to hit the max - note this will get put in the UI once the new fortune draws start
So TDLR: go to the bracket and division you are in, and find the number of maximum draws you can get. Then go to the 2nd table and see how much needs to be staked to get that amount.
In your example of needing 50k that is only to get 6 Draws each batch of 5 wins, but if you had only 2,500 SPS, then you would still get 1 draw every 5 wins.