You absolutely do not need a PhD for industry unless you want an R&D job in a handful of domains. A PhD is not simply learning more facts about a particular topic. It's an apprenticeship for conducting independently directed academic research. There are so many topics that you can not just learn from reading some online sources e.g. most experimental work. Most of the time spent in a typical PhD program is spent trying to solve problems that have no easy answers and no easy guidelines to follow. While you can definitely gain similar knowledge and experience in an industry setting, you almost never have the freedom to take the 3+ years often necessary to explore a narrow topic, struggle and fail repeatedly, be faced with and overcome crushing doubt and frustration, and do so in a generally supportive community.