Age doesn't matter, stability does
Although a database more than 30 years old, PostgreSQL has enjoyed a lot of growth in the last few years…
None of the dominant databases are young. They're dependent upon maths done in the 1960s that demonstrated the superiority of the relational model in nearly all situations. Get that, integrity and security right and the rest is gravy.
Would you trust your company's data to some start-up's database without a 30 year old track record?