If you're living in California and making $125,000 per year at a job, you're paying $33,000 in income taxes alone. Your 50% savings rate would be $62,500 - after taxes you have $92,000, so the person can live off of $30,000 per year. Rent alone can easily run $1,500 to $2,500 per month. This is an impossible scenario without even getting into the real costs of existing (ie bills, families, debts, vehicle & getting to work, accidents, problems, charity, social life, doing things).
My ex, who lives in Los Angeles, and makes $70k per year in the medical field, can't save more than $400 to $500 per month max after all costs and taxes. That savings is inevitably slashed in half due to once-per-year events that cost a few thousand dollars to fix. Her only salvation is her 401k.