To reiterate half of what you've said, but maybe in a slightly different way, the defense security clearance process is designed to determine how likely you are to be incentivized or coerced into revealing classified information.
The point of the deep dive is not to prove you've always been an upstanding citizen, but to look for factors that make you an easier target for foreign intelligence services such as:
1. Do you have any financial problems that could make you easier to buy off? (Bad credit, gambling problems)
2. Do you have any (real or perceived) addictions that might impair your judgement or can be leveraged against you? (drugs and DUIs)
3. Are you currently attempting to hide any criminal activity that you could be blackmailed with?
4. Do you have any sensitive foreign connections or other possible allegiances?
The point of the deep dive is not to prove you've always been an upstanding citizen, but to look for factors that make you an easier target for foreign intelligence services such as:
1. Do you have any financial problems that could make you easier to buy off? (Bad credit, gambling problems)
2. Do you have any (real or perceived) addictions that might impair your judgement or can be leveraged against you? (drugs and DUIs)
3. Are you currently attempting to hide any criminal activity that you could be blackmailed with?
4. Do you have any sensitive foreign connections or other possible allegiances?