More than bigger names what would really work like a charm would be mid range creators/influences with a strong niche. Pewdiepie involvement didn't do much for Dlive. Instead of one YouTuber with 10 million subscribers, we'll do much better with a small horde of creatos with 50K - 500K subscribers. Think some Anime Youtubers, Horror YouTubers, Educational Channel, Game/Film Theory analysis channel etc. Even if few of them leave, we'll have few more remaining. Also the platform will look more vibrant instead of looking like some Pewdiepie blockchain.
Big names will eventually join when there are enough active users. A fan community of a celerity will become a great incentive for a celebrity to join STEEM.
Yes, of course, start small.
To get some of the big guys of Instagram onboard would also cost more money than steemit makes in a year...