Agree completely. I like the point on disagreement of value and OP should be prepared to move on.
I just want to add that OP should negotiate for the future and not get too hung up on trying to recover the past or think they are entitled to any equity appreciation they missed out on. Sticking too much to principle might just leave resentment lingering. While it is possible to negotiate to make up for the past I think there is more value in focusing on the future.
ie. Even if OP negotiated harder now, the equity is unlikely to be gifted to make up for the past. It may come in the form of vesting options but that will likely be structured to only gain value from the time of grant (now) onwards. That... or OP will get lower % equity than would have been received in the past. Knowing this, I think it is still better to correct it going forwards than worry about any missed appreciation.
I just want to add that OP should negotiate for the future and not get too hung up on trying to recover the past or think they are entitled to any equity appreciation they missed out on. Sticking too much to principle might just leave resentment lingering. While it is possible to negotiate to make up for the past I think there is more value in focusing on the future.
ie. Even if OP negotiated harder now, the equity is unlikely to be gifted to make up for the past. It may come in the form of vesting options but that will likely be structured to only gain value from the time of grant (now) onwards. That... or OP will get lower % equity than would have been received in the past. Knowing this, I think it is still better to correct it going forwards than worry about any missed appreciation.