Under current prices buying hardware just to run local models is not worth it EVER, unless you already need the hardware for other reasons or you somehow value having no one else be able to possibly see your AI usage.

Let's be generous and assume you are able to get a RTX 5090 at MSRP ($2000) and ignore the rest of your hardware, then run a model that is the optimal size for the GPU. A 5090 has one of the best throughputs in AI inference for the price, which benefits the local AI cost-efficiency in our calculations. According to this reddit post it outputs Qwen2.5-Coder 32B at 30.6 tokens/s. https://www.reddit.com/r/LocalLLaMA/comments/1ir3rsl/inferen...

It's probably quantized, but let's again be generous and assume it's not quantized any more than models on OpenRouter. Also we assume you are able to keep this GPU busy with useful work 24/7 and ignore your electricity bill. At 30.6 tokens/s you're able to generate 993M output tokens in a year, which we can conveniently round up to a billion.

Currently the cheapest Qwen2.5-Coder 32B provider on OpenRouter that doesn't train on your input runs it at $0.06/M input and $0.15/M output tokens. So it would cost $150 to serve 1B tokens via API. Let's assume input costs are similar since providers have an incentive to price both input and output proportionately to cost, so $300 total to serve the same amount of tokens as a 5090 can produce in 1 year running constantly.

Conclusion: even with EVERY assumption in favor of the local GPU user, it still takes almost 7 years for running a local LLM to become worth it. (This doesn't take into account that API prices will most likely decrease over time, but also doesn't take into account that you can sell your GPU after the breakeven period. I think these two effects should mostly cancel out.)

In the real world in OP's case, you aren't running your model 24/7 on your MacBook; it's quantized and less accurate than the one on OpenRouter; a MacBook costs more and runs AI models a lot slower than a 5090; and you do need to pay electricity bills. If you only change one assumption and run the model only 1.5 hours a day instead of 24/7, then the breakeven period already goes up to more than 100 years instead of 7 years.

Basically, unless you absolutely NEED a laptop this expensive for other reasons, don't ever do this.