I spent a 5 years out of 40 working for a consulting firm, and I think it was valuable, as you get thrown in to all sorts of random things, which provides some great experience at dealing with stuff you barely knew existed before the customer walked into the door. This was mostly around the turn of the millennium (including Dotcom era).
The flip side was seeing some idiotic customers you had to build things for that clearly made zero sense, technical or business, and often led you to wonder about your sanity. I worked on one project for several months at which point the company pivoted to an unrelated business, and then refused to pay for the work done, as they no longer needed it. Another project was very successful in fixing their business issues, but they refused to pay for an extra week caused by a relatively major requirement change, so I had to leave the project incomplete. In another project the arguments about signing the contract took longer than the project did, so I was forced to work without any communication with the client.
The flip side was seeing some idiotic customers you had to build things for that clearly made zero sense, technical or business, and often led you to wonder about your sanity. I worked on one project for several months at which point the company pivoted to an unrelated business, and then refused to pay for the work done, as they no longer needed it. Another project was very successful in fixing their business issues, but they refused to pay for an extra week caused by a relatively major requirement change, so I had to leave the project incomplete. In another project the arguments about signing the contract took longer than the project did, so I was forced to work without any communication with the client.