Law firms are usually organized as LLPs, LLCs, or PCs these days, but bottom line that means ownership shares can't be freely transferred. You can't sell your stake, so there's no opportunity for a major liquidity event like you might experience as an employee compensated in stock at a corporation when the stock increases in value dramatically and you sell.

Worse yet, lawyers have to keep working to continue to receive equity compensation in the overwhelming majority of cases. So you can't retire and continue to make money from your equity stake. You can't even really cut back on the crazy hours. This answer covers it pretty thoroughly: https://www.quora.com/Do-partners-in-law-firms-keep-a-share-...