Direct investment in Estée Lauder Companies (NYSE: EL) or L'Oréal (ADR: LRLCY) puts you in premium hair care growth as serums gain virality and repeat purchase. Alternatively, gain indirect exposure through Procter & Gamble (NYSE: PG) or Unilever (NYSE: UL) whose portfolios include mass-market hair brands and vast retailer reach that benefit from rising consumer interest in scalp care. Or, launch a direct-to-consumer hair growth serum brand with targeted influencer marketing and fast manufacturing, then expand into salons and retailers as the category compounds.