Salah has been a key member of the Reds side since arriving from Roma.
He has helped them achieve Champions League glory, and put them within touching distance of the Premier League title.
'It's never easy to replace a player like that," Neville said on Sky's Monday Night Football ahead of Liverpool's 3-2 win over West Ham.
"I said 18 months ago I thought Mo Salah would leave Liverpool.
"I think it's a little bit more simple in the sense of why Liverpool fans maybe don't demonstrate that love for Salah, and it's affinity and loyalty.
"That's not a criticism of Mo Salah. I played with David Beckham, I played with Ruud van Nistelrooy, played with Cristiano Ronaldo - they wanted to aspire to win the Ballon d'Or, they wanted to be at Real Madrid, they wanted to be up in lights and play at the biggest clubs in the world.
"I think there's a feeling, affinity, loyalty, 'will he leave us?' I think he could.
"I think he is ultimately using Liverpool potentially as a stepping stone for his career.