NikafieNd the Pron required for the investments is indeed 6,250,000. However, according to the calculator your returns should be a total of 5,677,000 + your original 584.500 > expenditure (6250k).
Here is a list of my returns:
Yhilin:
Yhilin Arms Dealer: 20000 ProN
Premium Steel Stake Owner: 10000 ProN
Bank of Yhilin Core Lender: 150000 ProN
Special Supplier: 25000 ProN
Mine Processing: 100000 ProN
Yhilini Supplier: 5000 ProN
Slum Fighting Ring: 40000 ProN
Sex Fighting Ring: 60000 ProN
Yhilini Sex Shop: 75000 ProN
Private Mineshaft: 130000 ProN
Yhilini Mercenary: 15000 ProN
Yhilini Succubi Trade: 200000 ProN
Yhilini Brothel: 35000 ProN
Yhilini Airships: 100000 ProN
Ardoheim:
Ardoheim Magic Trade: 65000 ProN
Ivalan Bank: 225000 ProN
Ardan Bank: 300000 ProN
Ardford Supplier: 5000 ProN
Sanitation Mage Guild: 5000 ProN
Ardford Restaurant: 25000 ProN
Crystal Refiner: 55000 ProN
Stineford:
Stineford's Magic shop: 25000 ProN
Trading Pillar Rights: 100000 ProN
Bank of Stineford: 240000 ProN
Stineford's Weapons Shop: 75000 ProN
Stineford's Mine: 50000 ProN
Stineford's Succubus Bar: 10000 ProN
Iris Sewing Operation: 100000 ProN
Aram:
Desert Bounty Office: 5000 ProN
Eustrin Processor: 20000 ProN
Eustrin Manufacturer: 25000 ProN
Eustrin Guild: 250000 ProN
Darghelon/Gheldaron:
Min's Trade Route: 185000 ProN
Theltiar Flowhouse: 80000 ProN
Theltiar Rentals: 95000 ProN
Denmiel Archives: 20000 ProN
Denmiel Mushroom Farm: 40000 ProN
New Givini:
New Givini Trade: 100000 ProN
Givini Tunnels: 300000 ProN
Givini Smithing: 10000 ProN
Givini Orc Merchant: 200000 ProN
Bank of Givini: 300000 ProN
Givini Teahouse Chain: 30000 ProN
Chalice States:
Chalice States Trade: 100000 ProN
Gasm Falls Trade: 110000 ProN
Lustlord Temples: 50000 ProN
Succubus Band Tour: 2000 ProN
Succubus Armorer: 10000 ProN
Tak'Kan:
Tak'Kan Trade: 100000 ProN
Tarran'kan Housing: 50000 ProN
Hall of Mental Strength: 25000 ProN
Illustrious Booze Shack: 50000 ProN
Tarran'Kan Trade Upgrade: 50000 ProN
Cee'Kan Shipping: 200000 ProN
The Lonely Sailor: 100000 ProN
Tak'Kan Mine: 125000 ProN
Tradersmasher's Guild: 175000 ProN
Erosia:
Erosian Trade: 250000 ProN
Kyangan Smithing: 25000 ProN
Kyangan Agriculture: 350000 ProN
Rodak:
Total Profit: 5677000