ISRU at the KSP to save money?

[Kerbart]

Option 1

• Build "rocket" consisting of three large kerbodyne tanks and put it on the launch pad
  
• Load her up with fuel gathered from the ISRU. This might or might not be an intensily aggravating experience, depending on how patient you are
  
• Recover vessel
  
• Profit!

Option 2

• Right Alt + F12

[r_rolo1]

Option 1 can be run in Hard mode, Option 2 can't

[AbacusWizard]

Option 1 can be run in Hard mode, Option 2 can't

Does opening your savefile with a text editor still work in hard mode?

[Stoney3K]

Does opening your savefile with a text editor still work in hard mode?

What's the point of hard mode if you're trying to cheat around it?

Sure, the ISRU can be used to print money, but you'll get bored of it easily because it takes all challenge out of the game. Might as well play science career then.

The only situation I would use it is if I was in a short-term cash flow emergency, but not as a regular source of income.