I don't see it how much is enough, but rather how much offers you a solid base to invest and get a steady monthly revenue. For example I will feel good to earn $2,500 per month (while holding also a job), thus the question is what amount of money do I need to make that happen? For example having $200k invested in HBD and getting 15% APR per year, that would translate into $2,500 per month. That would be a good start, but requires also risk diversification. Getting to $10k per month would mean a great life in my opinion, while still holding a job.