While AI start-ups struggle, Coinbase Global is now posting more than $2.5 billion in profit each year.Tech investors have a big decision to make these days. Should they chase after high-growth artificial intelligence (AI) start-ups with little in the way of profitability, or should they focus on entrenched tech leaders with billions of dollars in profits flowing in each year?If revenue and profitability matter to you as an investor, then it's impossible not to sit up and take notice of Coinbase Global (COI ...