Buyers in condo-hotels across the country are turning to the courts to get their money back, alleging that condo-hotel developers violated securities laws in selling the units. The buyers argue that purchasing a residential unit in a condo-hotel is akin to buying stock, and the sales should therefore have been regulated by the Securities and Exchange Commission. The SEC would require developers to use agents licensed to sell both real estate and securities. But developers’ lawyers say the legal argument doesn’t make sense. The decisions in these court cases could determine whether the condo-hotel model survives.